diff --git a/exercises/00_intro/intro1.rs b/exercises/00_intro/intro1.rs
index 5dd18b45..0979dc70 100644
--- a/exercises/00_intro/intro1.rs
+++ b/exercises/00_intro/intro1.rs
@@ -13,8 +13,6 @@
 // Execute `rustlings hint intro1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     println!("Hello and");
     println!(r#"       welcome to...                      "#);
diff --git a/exercises/00_intro/intro2.rs b/exercises/00_intro/intro2.rs
index a28ad3dc..acb730db 100644
--- a/exercises/00_intro/intro2.rs
+++ b/exercises/00_intro/intro2.rs
@@ -5,8 +5,6 @@
 // Execute `rustlings hint intro2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    printline!("Hello there!")
+    println!("Hello there!")
 }
diff --git a/exercises/01_variables/variables1.rs b/exercises/01_variables/variables1.rs
index b3e089a5..98a0cf22 100644
--- a/exercises/01_variables/variables1.rs
+++ b/exercises/01_variables/variables1.rs
@@ -5,9 +5,7 @@
 // Execute `rustlings hint variables1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    x = 5;
+    let x = 5;
     println!("x has the value {}", x);
 }
diff --git a/exercises/01_variables/variables2.rs b/exercises/01_variables/variables2.rs
index e1c23edf..59f9a023 100644
--- a/exercises/01_variables/variables2.rs
+++ b/exercises/01_variables/variables2.rs
@@ -3,10 +3,8 @@
 // Execute `rustlings hint variables2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let x;
+    let x = 10;
     if x == 10 {
         println!("x is ten!");
     } else {
diff --git a/exercises/01_variables/variables3.rs b/exercises/01_variables/variables3.rs
index 86bed419..be2adb5e 100644
--- a/exercises/01_variables/variables3.rs
+++ b/exercises/01_variables/variables3.rs
@@ -3,9 +3,7 @@
 // Execute `rustlings hint variables3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let x: i32;
+    let x: i32 = 0;
     println!("Number {}", x);
 }
diff --git a/exercises/01_variables/variables4.rs b/exercises/01_variables/variables4.rs
index 5394f394..c75843ea 100644
--- a/exercises/01_variables/variables4.rs
+++ b/exercises/01_variables/variables4.rs
@@ -3,10 +3,8 @@
 // Execute `rustlings hint variables4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let x = 3;
+    let mut x = 3;
     println!("Number {}", x);
     x = 5; // don't change this line
     println!("Number {}", x);
diff --git a/exercises/01_variables/variables5.rs b/exercises/01_variables/variables5.rs
index a29b38be..19ce9d66 100644
--- a/exercises/01_variables/variables5.rs
+++ b/exercises/01_variables/variables5.rs
@@ -3,11 +3,9 @@
 // Execute `rustlings hint variables5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let number = "T-H-R-E-E"; // don't change this line
     println!("Spell a Number : {}", number);
-    number = 3; // don't rename this variable
+    let number = 3; // don't rename this variable
     println!("Number plus two is : {}", number + 2);
 }
diff --git a/exercises/01_variables/variables6.rs b/exercises/01_variables/variables6.rs
index 853183ba..95bac556 100644
--- a/exercises/01_variables/variables6.rs
+++ b/exercises/01_variables/variables6.rs
@@ -3,9 +3,7 @@
 // Execute `rustlings hint variables6` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-const NUMBER = 3;
+const NUMBER: i32 = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }
diff --git a/exercises/02_functions/functions1.rs b/exercises/02_functions/functions1.rs
index 40ed9a07..745ba54d 100644
--- a/exercises/02_functions/functions1.rs
+++ b/exercises/02_functions/functions1.rs
@@ -3,8 +3,8 @@
 // Execute `rustlings hint functions1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     call_me();
 }
+
+fn call_me() {}
diff --git a/exercises/02_functions/functions2.rs b/exercises/02_functions/functions2.rs
index 5154f34d..7af8196a 100644
--- a/exercises/02_functions/functions2.rs
+++ b/exercises/02_functions/functions2.rs
@@ -3,13 +3,11 @@
 // Execute `rustlings hint functions2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     call_me(3);
 }
 
-fn call_me(num:) {
+fn call_me(num: i32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }
diff --git a/exercises/02_functions/functions3.rs b/exercises/02_functions/functions3.rs
index 74f44d6d..c201ec0e 100644
--- a/exercises/02_functions/functions3.rs
+++ b/exercises/02_functions/functions3.rs
@@ -3,10 +3,8 @@
 // Execute `rustlings hint functions3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    call_me();
+    call_me(0);
 }
 
 fn call_me(num: u32) {
diff --git a/exercises/02_functions/functions4.rs b/exercises/02_functions/functions4.rs
index 77c4b2aa..aec6cf35 100644
--- a/exercises/02_functions/functions4.rs
+++ b/exercises/02_functions/functions4.rs
@@ -8,14 +8,12 @@
 // Execute `rustlings hint functions4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let original_price = 51;
     println!("Your sale price is {}", sale_price(original_price));
 }
 
-fn sale_price(price: i32) -> {
+fn sale_price(price: i32) -> i32 {
     if is_even(price) {
         price - 10
     } else {
diff --git a/exercises/02_functions/functions5.rs b/exercises/02_functions/functions5.rs
index f1b63f48..c51bea9f 100644
--- a/exercises/02_functions/functions5.rs
+++ b/exercises/02_functions/functions5.rs
@@ -3,13 +3,11 @@
 // Execute `rustlings hint functions5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let answer = square(3);
     println!("The square of 3 is {}", answer);
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }
diff --git a/exercises/03_if/if1.rs b/exercises/03_if/if1.rs
index 4734d78f..c1692165 100644
--- a/exercises/03_if/if1.rs
+++ b/exercises/03_if/if1.rs
@@ -2,13 +2,16 @@
 //
 // Execute `rustlings hint if1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub fn bigger(a: i32, b: i32) -> i32 {
     // Complete this function to return the bigger number!
     // Do not use:
     // - another function call
     // - additional variables
+    if (a < b) {
+        b
+    } else { 
+        a
+    }
 }
 
 // Don't mind this for now :)
diff --git a/exercises/03_if/if2.rs b/exercises/03_if/if2.rs
index f512f13f..90e327b8 100644
--- a/exercises/03_if/if2.rs
+++ b/exercises/03_if/if2.rs
@@ -5,13 +5,13 @@
 //
 // Execute `rustlings hint if2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub fn foo_if_fizz(fizzish: &str) -> &str {
     if fizzish == "fizz" {
         "foo"
+    } else if (fizzish == "fuzz") {
+        "bar"
     } else {
-        1
+        "baz"
     }
 }
 
diff --git a/exercises/03_if/if3.rs b/exercises/03_if/if3.rs
index 16962740..f76aabce 100644
--- a/exercises/03_if/if3.rs
+++ b/exercises/03_if/if3.rs
@@ -2,17 +2,15 @@
 //
 // Execute `rustlings hint if3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub fn animal_habitat(animal: &str) -> &'static str {
     let identifier = if animal == "crab" {
         1
     } else if animal == "gopher" {
-        2.0
+        2
     } else if animal == "snake" {
         3
     } else {
-        "Unknown"
+        4
     };
 
     // DO NOT CHANGE THIS STATEMENT BELOW
diff --git a/exercises/04_primitive_types/primitive_types1.rs b/exercises/04_primitive_types/primitive_types1.rs
index 36633400..67585c12 100644
--- a/exercises/04_primitive_types/primitive_types1.rs
+++ b/exercises/04_primitive_types/primitive_types1.rs
@@ -3,8 +3,6 @@
 // Fill in the rest of the line that has code missing! No hints, there's no
 // tricks, just get used to typing these :)
 
-// I AM NOT DONE
-
 fn main() {
     // Booleans (`bool`)
 
@@ -13,7 +11,7 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening = false;
     if is_evening {
         println!("Good evening!");
     }
diff --git a/exercises/04_primitive_types/primitive_types2.rs b/exercises/04_primitive_types/primitive_types2.rs
index f1616ed3..ecbd251a 100644
--- a/exercises/04_primitive_types/primitive_types2.rs
+++ b/exercises/04_primitive_types/primitive_types2.rs
@@ -3,8 +3,6 @@
 // Fill in the rest of the line that has code missing! No hints, there's no
 // tricks, just get used to typing these :)
 
-// I AM NOT DONE
-
 fn main() {
     // Characters (`char`)
 
@@ -19,7 +17,7 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
+    let your_character = 'J';
     // Try a letter, try a number, try a special character, try a character
     // from a different language than your own, try an emoji!
     if your_character.is_alphabetic() {
diff --git a/exercises/04_primitive_types/primitive_types3.rs b/exercises/04_primitive_types/primitive_types3.rs
index 8b0de44e..e0268a39 100644
--- a/exercises/04_primitive_types/primitive_types3.rs
+++ b/exercises/04_primitive_types/primitive_types3.rs
@@ -5,10 +5,8 @@
 // Execute `rustlings hint primitive_types3` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let a = ???
+    let a = 0..100;
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");
diff --git a/exercises/04_primitive_types/primitive_types4.rs b/exercises/04_primitive_types/primitive_types4.rs
index d44d8776..be863098 100644
--- a/exercises/04_primitive_types/primitive_types4.rs
+++ b/exercises/04_primitive_types/primitive_types4.rs
@@ -5,13 +5,11 @@
 // Execute `rustlings hint primitive_types4` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn slice_out_of_array() {
     let a = [1, 2, 3, 4, 5];
 
-    let nice_slice = ???
+    let nice_slice = &a[1..4];
 
     assert_eq!([2, 3, 4], nice_slice)
 }
diff --git a/exercises/04_primitive_types/primitive_types5.rs b/exercises/04_primitive_types/primitive_types5.rs
index f646986e..7a330445 100644
--- a/exercises/04_primitive_types/primitive_types5.rs
+++ b/exercises/04_primitive_types/primitive_types5.rs
@@ -5,11 +5,9 @@
 // Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name, age) = cat;
 
     println!("{} is {} years old.", name, age);
 }
diff --git a/exercises/04_primitive_types/primitive_types6.rs b/exercises/04_primitive_types/primitive_types6.rs
index 07cc46c6..0ed7cfd2 100644
--- a/exercises/04_primitive_types/primitive_types6.rs
+++ b/exercises/04_primitive_types/primitive_types6.rs
@@ -6,13 +6,11 @@
 // Execute `rustlings hint primitive_types6` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn indexing_tuple() {
     let numbers = (1, 2, 3);
     // Replace below ??? with the tuple indexing syntax.
-    let second = ???;
+    let second = numbers.1;
 
     assert_eq!(2, second,
         "This is not the 2nd number in the tuple!")
diff --git a/exercises/05_vecs/vecs1.rs b/exercises/05_vecs/vecs1.rs
index 65b7a7f8..46bd28a5 100644
--- a/exercises/05_vecs/vecs1.rs
+++ b/exercises/05_vecs/vecs1.rs
@@ -7,11 +7,9 @@
 //
 // Execute `rustlings hint vecs1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn array_and_vec() -> ([i32; 4], Vec<i32>) {
     let a = [10, 20, 30, 40]; // a plain array
-    let v = // TODO: declare your vector here with the macro for vectors
+    let v = vec!(10, 20, 30, 40); // TODO: declare your vector here with the macro for vectors
 
     (a, v)
 }
diff --git a/exercises/05_vecs/vecs2.rs b/exercises/05_vecs/vecs2.rs
index e92c970a..91f9f80e 100644
--- a/exercises/05_vecs/vecs2.rs
+++ b/exercises/05_vecs/vecs2.rs
@@ -7,13 +7,11 @@
 //
 // Execute `rustlings hint vecs2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
     for element in v.iter_mut() {
         // TODO: Fill this up so that each element in the Vec `v` is
         // multiplied by 2.
-        ???
+        *element = *element * 2
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
@@ -24,7 +22,7 @@ fn vec_map(v: &Vec<i32>) -> Vec<i32> {
     v.iter().map(|element| {
         // TODO: Do the same thing as above - but instead of mutating the
         // Vec, you can just return the new number!
-        ???
+        *element * 2
     }).collect()
 }
 
diff --git a/exercises/06_move_semantics/move_semantics1.rs b/exercises/06_move_semantics/move_semantics1.rs
index e0639375..3b76ccc6 100644
--- a/exercises/06_move_semantics/move_semantics1.rs
+++ b/exercises/06_move_semantics/move_semantics1.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
@@ -15,7 +13,7 @@ fn main() {
 }
 
 fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let vec = vec;
+    let mut vec = vec;
 
     vec.push(88);
 
diff --git a/exercises/06_move_semantics/move_semantics2.rs b/exercises/06_move_semantics/move_semantics2.rs
index baf6bcc9..e3c0402f 100644
--- a/exercises/06_move_semantics/move_semantics2.rs
+++ b/exercises/06_move_semantics/move_semantics2.rs
@@ -5,13 +5,11 @@
 // Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(vec0.clone());
 
     assert_eq!(vec0, vec![22, 44, 66]);
     assert_eq!(vec1, vec![22, 44, 66, 88]);
diff --git a/exercises/06_move_semantics/move_semantics3.rs b/exercises/06_move_semantics/move_semantics3.rs
index 7af9e694..d473bb68 100644
--- a/exercises/06_move_semantics/move_semantics3.rs
+++ b/exercises/06_move_semantics/move_semantics3.rs
@@ -6,8 +6,6 @@
 // Execute `rustlings hint move_semantics3` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
@@ -17,7 +15,7 @@ fn main() {
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(mut vec: Vec<i32>) -> Vec<i32> {
     vec.push(88);
 
     vec
diff --git a/exercises/06_move_semantics/move_semantics4.rs b/exercises/06_move_semantics/move_semantics4.rs
index 80b49dba..1e76b213 100644
--- a/exercises/06_move_semantics/move_semantics4.rs
+++ b/exercises/06_move_semantics/move_semantics4.rs
@@ -7,13 +7,11 @@
 // Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec();
 
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
@@ -21,7 +19,7 @@ fn main() {
 // `fill_vec()` no longer takes `vec: Vec<i32>` as argument - don't change this!
 fn fill_vec() -> Vec<i32> {
     // Instead, let's create and fill the Vec in here - how do you do that?
-    let mut vec = vec;
+    let mut vec = vec![22, 44, 66];
 
     vec.push(88);
 
diff --git a/exercises/06_move_semantics/move_semantics5.rs b/exercises/06_move_semantics/move_semantics5.rs
index 267bdccc..3e26f266 100644
--- a/exercises/06_move_semantics/move_semantics5.rs
+++ b/exercises/06_move_semantics/move_semantics5.rs
@@ -6,14 +6,12 @@
 // Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let mut x = 100;
     let y = &mut x;
-    let z = &mut x;
     *y += 100;
+    let z = &mut x;
     *z += 1000;
     assert_eq!(x, 1200);
 }
diff --git a/exercises/06_move_semantics/move_semantics6.rs b/exercises/06_move_semantics/move_semantics6.rs
index cace4ca6..1780033f 100644
--- a/exercises/06_move_semantics/move_semantics6.rs
+++ b/exercises/06_move_semantics/move_semantics6.rs
@@ -5,12 +5,10 @@
 // Execute `rustlings hint move_semantics6` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     let data = "Rust is great!".to_string();
 
-    get_char(data);
+    get_char(data.clone());
 
     string_uppercase(&data);
 }
@@ -22,7 +20,7 @@ fn get_char(data: String) -> char {
 
 // Should take ownership
 fn string_uppercase(mut data: &String) {
-    data = &data.to_uppercase();
+    let data = &data.to_uppercase();
 
     println!("{}", data);
 }
diff --git a/exercises/07_structs/structs1.rs b/exercises/07_structs/structs1.rs
index 5fa5821c..3b300277 100644
--- a/exercises/07_structs/structs1.rs
+++ b/exercises/07_structs/structs1.rs
@@ -5,13 +5,16 @@
 // Execute `rustlings hint structs1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
+#[derive(PartialEq)]
 struct ColorClassicStruct {
     // TODO: Something goes here
+    red: u32,
+    blue: u32,
+    green: u32,
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+#[derive(Debug)]
+struct ColorTupleStruct(u32, u32, u32);
 
 #[derive(Debug)]
 struct UnitLikeStruct;
@@ -23,7 +26,11 @@ mod tests {
     #[test]
     fn classic_c_structs() {
         // TODO: Instantiate a classic c struct!
-        // let green =
+        let green = ColorClassicStruct {
+            red: 0,
+            green: 255,
+            blue: 0
+        };
 
         assert_eq!(green.red, 0);
         assert_eq!(green.green, 255);
@@ -33,7 +40,7 @@ mod tests {
     #[test]
     fn tuple_structs() {
         // TODO: Instantiate a tuple struct!
-        // let green =
+        let green = ColorTupleStruct(0, 255, 0);
 
         assert_eq!(green.0, 0);
         assert_eq!(green.1, 255);
@@ -43,7 +50,7 @@ mod tests {
     #[test]
     fn unit_structs() {
         // TODO: Instantiate a unit-like struct!
-        // let unit_like_struct =
+        let unit_like_struct = UnitLikeStruct;
         let message = format!("{:?}s are fun!", unit_like_struct);
 
         assert_eq!(message, "UnitLikeStructs are fun!");
diff --git a/exercises/07_structs/structs2.rs b/exercises/07_structs/structs2.rs
index 328567f0..536eb238 100644
--- a/exercises/07_structs/structs2.rs
+++ b/exercises/07_structs/structs2.rs
@@ -5,8 +5,6 @@
 // Execute `rustlings hint structs2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Order {
     name: String,
@@ -38,7 +36,12 @@ mod tests {
     fn your_order() {
         let order_template = create_order_template();
         // TODO: Create your own order using the update syntax and template above!
-        // let your_order =
+        let your_order = Order {
+            name: "Hacker in Rust".to_string(),
+            count: 1,
+            ..order_template
+        };
+
         assert_eq!(your_order.name, "Hacker in Rust");
         assert_eq!(your_order.year, order_template.year);
         assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
diff --git a/exercises/07_structs/structs3.rs b/exercises/07_structs/structs3.rs
index 7cda5af1..dde7fba3 100644
--- a/exercises/07_structs/structs3.rs
+++ b/exercises/07_structs/structs3.rs
@@ -7,8 +7,6 @@
 // Execute `rustlings hint structs3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Package {
     sender_country: String,
@@ -31,12 +29,18 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
+    fn is_international(&self) -> bool {
         // Something goes here...
+        if &self.sender_country == &self.recipient_country {
+            false
+        } else {
+            true
+        }
     }
 
-    fn get_fees(&self, cents_per_gram: u32) -> ??? {
+    fn get_fees(&self, cents_per_gram: u32) -> u32 {
         // Something goes here...
+        &self.weight_in_grams * cents_per_gram
     }
 }
 
diff --git a/exercises/08_enums/enums1.rs b/exercises/08_enums/enums1.rs
index 25525b25..92c71176 100644
--- a/exercises/08_enums/enums1.rs
+++ b/exercises/08_enums/enums1.rs
@@ -2,11 +2,13 @@
 //
 // No hints this time! ;)
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
     // TODO: define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor
 }
 
 fn main() {
diff --git a/exercises/08_enums/enums2.rs b/exercises/08_enums/enums2.rs
index df93fe0f..55ba093d 100644
--- a/exercises/08_enums/enums2.rs
+++ b/exercises/08_enums/enums2.rs
@@ -3,11 +3,13 @@
 // Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
     // TODO: define the different variants used below
+    Move { x: u32, y: u32 },
+    Echo(String),
+    ChangeColor(u32, u32, u32),
+    Quit
 }
 
 impl Message {
diff --git a/exercises/08_enums/enums3.rs b/exercises/08_enums/enums3.rs
index 92d18c46..712729c2 100644
--- a/exercises/08_enums/enums3.rs
+++ b/exercises/08_enums/enums3.rs
@@ -5,10 +5,12 @@
 // Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 enum Message {
     // TODO: implement the message variant types based on their usage below
+    ChangeColor(u8, u8, u8),
+    Echo(String),
+    Move(Point),
+    Quit
 }
 
 struct Point {
@@ -44,6 +46,12 @@ impl State {
         // TODO: create a match expression to process the different message variants
         // Remember: When passing a tuple as a function argument, you'll need extra parentheses:
         // fn function((t, u, p, l, e))
+        match message {
+            Message::ChangeColor(r, g, b) => &self.change_color((r, g, b)),
+            Message::Move(point) => &self.move_position(point),
+            Message::Echo(string) => &self.echo(string),
+            Message::Quit => &self.quit()
+        };
     }
 }
 
diff --git a/exercises/09_strings/strings1.rs b/exercises/09_strings/strings1.rs
index f50e1fa9..e789b8f0 100644
--- a/exercises/09_strings/strings1.rs
+++ b/exercises/09_strings/strings1.rs
@@ -5,13 +5,11 @@
 // Execute `rustlings hint strings1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let answer = current_favorite_color();
     println!("My current favorite color is {}", answer);
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    "blue".to_string()
 }
diff --git a/exercises/09_strings/strings2.rs b/exercises/09_strings/strings2.rs
index 4d95d16a..ca16ea3d 100644
--- a/exercises/09_strings/strings2.rs
+++ b/exercises/09_strings/strings2.rs
@@ -5,11 +5,9 @@
 // Execute `rustlings hint strings2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let word = String::from("green"); // Try not changing this line :)
-    if is_a_color_word(word) {
+    if is_a_color_word(&word) {
         println!("That is a color word I know!");
     } else {
         println!("That is not a color word I know.");
diff --git a/exercises/09_strings/strings3.rs b/exercises/09_strings/strings3.rs
index b29f9325..4d4ae376 100644
--- a/exercises/09_strings/strings3.rs
+++ b/exercises/09_strings/strings3.rs
@@ -3,21 +3,20 @@
 // Execute `rustlings hint strings3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn trim_me(input: &str) -> String {
     // TODO: Remove whitespace from both ends of a string!
-    ???
+    input.trim().to_string()
 }
 
 fn compose_me(input: &str) -> String {
     // TODO: Add " world!" to the string! There's multiple ways to do this!
-    ???
+    format!("{} world!", input)
+    // input.to_owned() + " world!"
 }
 
 fn replace_me(input: &str) -> String {
     // TODO: Replace "cars" in the string with "balloons"!
-    ???
+    input.to_string().replace("cars", "balloons")
 }
 
 #[cfg(test)]
diff --git a/exercises/09_strings/strings4.rs b/exercises/09_strings/strings4.rs
index e8c54acc..9c2a0c72 100644
--- a/exercises/09_strings/strings4.rs
+++ b/exercises/09_strings/strings4.rs
@@ -7,8 +7,6 @@
 //
 // No hints this time!
 
-// I AM NOT DONE
-
 fn string_slice(arg: &str) {
     println!("{}", arg);
 }
@@ -17,14 +15,14 @@ fn string(arg: String) {
 }
 
 fn main() {
-    ???("blue");
-    ???("red".to_string());
-    ???(String::from("hi"));
-    ???("rust is fun!".to_owned());
-    ???("nice weather".into());
-    ???(format!("Interpolation {}", "Station"));
-    ???(&String::from("abc")[0..1]);
-    ???("  hello there ".trim());
-    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+    string_slice("blue");
+    string("red".to_string());
+    string(String::from("hi"));
+    string("rust is fun!".to_owned());
+    string("nice weather".into());
+    string(format!("Interpolation {}", "Station"));
+    string_slice(&String::from("abc")[0..1]);
+    string_slice("  hello there ".trim());
+    string("Happy Monday!".to_string().replace("Mon", "Tues"));
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
 }
diff --git a/exercises/10_modules/modules1.rs b/exercises/10_modules/modules1.rs
index 9eb5a48b..a26f5c45 100644
--- a/exercises/10_modules/modules1.rs
+++ b/exercises/10_modules/modules1.rs
@@ -3,15 +3,13 @@
 // Execute `rustlings hint modules1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 mod sausage_factory {
     // Don't let anybody outside of this module see this!
     fn get_secret_recipe() -> String {
         String::from("Ginger")
     }
 
-    fn make_sausage() {
+    pub fn make_sausage() {
         get_secret_recipe();
         println!("sausage!");
     }
diff --git a/exercises/10_modules/modules2.rs b/exercises/10_modules/modules2.rs
index 04154543..8cf30d3b 100644
--- a/exercises/10_modules/modules2.rs
+++ b/exercises/10_modules/modules2.rs
@@ -7,19 +7,17 @@
 // Execute `rustlings hint modules2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 mod delicious_snacks {
     // TODO: Fix these use statements
-    use self::fruits::PEAR as ???
-    use self::veggies::CUCUMBER as ???
+    pub use self::fruits::PEAR as fruit;
+    pub use self::veggies::CUCUMBER as veggie;
 
-    mod fruits {
+    pub mod fruits {
         pub const PEAR: &'static str = "Pear";
         pub const APPLE: &'static str = "Apple";
     }
 
-    mod veggies {
+    pub mod veggies {
         pub const CUCUMBER: &'static str = "Cucumber";
         pub const CARROT: &'static str = "Carrot";
     }
diff --git a/exercises/10_modules/modules3.rs b/exercises/10_modules/modules3.rs
index f2bb0503..d1e3ab4f 100644
--- a/exercises/10_modules/modules3.rs
+++ b/exercises/10_modules/modules3.rs
@@ -8,10 +8,8 @@
 // Execute `rustlings hint modules3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 // TODO: Complete this use statement
-use ???
+use std::time::{SystemTime, UNIX_EPOCH};
 
 fn main() {
     match SystemTime::now().duration_since(UNIX_EPOCH) {
diff --git a/exercises/11_hashmaps/hashmaps1.rs b/exercises/11_hashmaps/hashmaps1.rs
index 80829eaa..1279c8b7 100644
--- a/exercises/11_hashmaps/hashmaps1.rs
+++ b/exercises/11_hashmaps/hashmaps1.rs
@@ -11,15 +11,15 @@
 // Execute `rustlings hint hashmaps1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 fn fruit_basket() -> HashMap<String, u32> {
-    let mut basket = // TODO: declare your hash map here.
+    let mut basket = HashMap::new(); // TODO: declare your hash map here.
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
+    basket.insert(String::from("orange"), 3);
+    basket.insert(String::from("peach"), 4);
 
     // TODO: Put more fruits in your basket here.
 
diff --git a/exercises/11_hashmaps/hashmaps2.rs b/exercises/11_hashmaps/hashmaps2.rs
index a5925690..2fe4039f 100644
--- a/exercises/11_hashmaps/hashmaps2.rs
+++ b/exercises/11_hashmaps/hashmaps2.rs
@@ -14,8 +14,6 @@
 // Execute `rustlings hint hashmaps2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(Hash, PartialEq, Eq)]
@@ -40,6 +38,7 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
         // TODO: Insert new fruits if they are not already present in the
         // basket. Note that you are not allowed to put any type of fruit that's
         // already present!
+        basket.entry(fruit).or_insert(1);
     }
 }
 
@@ -81,7 +80,7 @@ mod tests {
         let count = basket.values().sum::<u32>();
         assert!(count > 11);
     }
-    
+
     #[test]
     fn all_fruit_types_in_basket() {
         let mut basket = get_fruit_basket();
diff --git a/exercises/11_hashmaps/hashmaps3.rs b/exercises/11_hashmaps/hashmaps3.rs
index 08e977c3..c2512015 100644
--- a/exercises/11_hashmaps/hashmaps3.rs
+++ b/exercises/11_hashmaps/hashmaps3.rs
@@ -14,8 +14,6 @@
 // Execute `rustlings hint hashmaps3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 // A structure to store the goal details of a team.
@@ -39,7 +37,21 @@ fn build_scores_table(results: String) -> HashMap<String, Team> {
         // will be the number of goals conceded from team_2, and similarly
         // goals scored by team_2 will be the number of goals conceded by
         // team_1.
+        let team1 = scores.entry(team_1_name).or_insert(Team {
+            goals_scored: 0,
+            goals_conceded: 0,
+        });
+        team1.goals_scored += team_1_score;
+        team1.goals_conceded += team_2_score;
+
+        let team2 = scores.entry(team_2_name).or_insert(Team {
+            goals_scored: 0,
+            goals_conceded: 0,
+        });
+        team2.goals_scored += team_2_score;
+        team2.goals_conceded += team_1_score;
     }
+
     scores
 }
 
diff --git a/exercises/12_options/options1.rs b/exercises/12_options/options1.rs
index e131b48b..d3c46123 100644
--- a/exercises/12_options/options1.rs
+++ b/exercises/12_options/options1.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint options1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 // This function returns how much icecream there is left in the fridge.
 // If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them
 // all, so there'll be no more left :(
@@ -13,7 +11,13 @@ fn maybe_icecream(time_of_day: u16) -> Option<u16> {
     // value of 0 The Option output should gracefully handle cases where
     // time_of_day > 23.
     // TODO: Complete the function body - remember to return an Option!
-    ???
+    if time_of_day < 22 {
+        Some(5)
+    } else if time_of_day > 23 {
+        None
+    } else {
+        Some(0)
+    }
 }
 
 #[cfg(test)]
@@ -34,6 +38,6 @@ mod tests {
         // TODO: Fix this test. How do you get at the value contained in the
         // Option?
         let icecreams = maybe_icecream(12);
-        assert_eq!(icecreams, 5);
+        assert_eq!(icecreams.unwrap(), 5);
     }
 }
diff --git a/exercises/12_options/options2.rs b/exercises/12_options/options2.rs
index 4d998e7d..cbf281ff 100644
--- a/exercises/12_options/options2.rs
+++ b/exercises/12_options/options2.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint options2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
@@ -13,7 +11,7 @@ mod tests {
         let optional_target = Some(target);
 
         // TODO: Make this an if let statement whose value is "Some" type
-        word = optional_target {
+        if let Some(word) = optional_target {
             assert_eq!(word, target);
         }
     }
@@ -32,7 +30,7 @@ mod tests {
         // TODO: make this a while let statement - remember that vector.pop also
         // adds another layer of Option<T>. You can stack `Option<T>`s into
         // while let and if let.
-        integer = optional_integers.pop() {
+        while let Some(Some(integer)) = optional_integers.pop() {
             assert_eq!(integer, cursor);
             cursor -= 1;
         }
diff --git a/exercises/12_options/options3.rs b/exercises/12_options/options3.rs
index 23c15eab..bca3cff5 100644
--- a/exercises/12_options/options3.rs
+++ b/exercises/12_options/options3.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint options3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 struct Point {
     x: i32,
     y: i32,
@@ -14,7 +12,7 @@ fn main() {
     let y: Option<Point> = Some(Point { x: 100, y: 200 });
 
     match y {
-        Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
+        Some(ref p) => println!("Co-ordinates are {},{} ", p.x, p.y),
         _ => panic!("no match!"),
     }
     y; // Fix without deleting this line.
diff --git a/exercises/13_error_handling/errors1.rs b/exercises/13_error_handling/errors1.rs
index 0ba59a57..3365aa23 100644
--- a/exercises/13_error_handling/errors1.rs
+++ b/exercises/13_error_handling/errors1.rs
@@ -9,14 +9,12 @@
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-pub fn generate_nametag_text(name: String) -> Option<String> {
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
     if name.is_empty() {
         // Empty names aren't allowed.
-        None
+        Err("`name` was empty; it must be nonempty.".to_string())
     } else {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     }
 }
 
diff --git a/exercises/13_error_handling/errors2.rs b/exercises/13_error_handling/errors2.rs
index 631fe67f..3058229f 100644
--- a/exercises/13_error_handling/errors2.rs
+++ b/exercises/13_error_handling/errors2.rs
@@ -19,8 +19,6 @@
 // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
@@ -28,7 +26,10 @@ pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let cost_per_item = 5;
     let qty = item_quantity.parse::<i32>();
 
-    Ok(qty * cost_per_item + processing_fee)
+    match qty {
+        Ok(qty) => Ok(qty * cost_per_item + processing_fee),
+        Err(err) => Err(err)
+    }
 }
 
 #[cfg(test)]
diff --git a/exercises/13_error_handling/errors3.rs b/exercises/13_error_handling/errors3.rs
index d42d3b17..bc88adfd 100644
--- a/exercises/13_error_handling/errors3.rs
+++ b/exercises/13_error_handling/errors3.rs
@@ -7,11 +7,9 @@
 // Execute `rustlings hint errors3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
-fn main() {
+fn main() -> Result<(), ParseIntError> {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
@@ -23,6 +21,8 @@ fn main() {
         tokens -= cost;
         println!("You now have {} tokens.", tokens);
     }
+
+    Ok(())
 }
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
diff --git a/exercises/13_error_handling/errors4.rs b/exercises/13_error_handling/errors4.rs
index d6d6fcb6..76bbd03a 100644
--- a/exercises/13_error_handling/errors4.rs
+++ b/exercises/13_error_handling/errors4.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
 
@@ -17,7 +15,13 @@ enum CreationError {
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
         // Hmm... Why is this always returning an Ok value?
-        Ok(PositiveNonzeroInteger(value as u64))
+        if (value > 0) {
+            Ok(PositiveNonzeroInteger(value as u64))
+        } else if (value < 0) {
+            Err(CreationError::Negative)
+        } else {
+            Err(CreationError::Zero)
+        }
     }
 }
 
diff --git a/exercises/13_error_handling/errors5.rs b/exercises/13_error_handling/errors5.rs
index 92461a7e..797a60d4 100644
--- a/exercises/13_error_handling/errors5.rs
+++ b/exercises/13_error_handling/errors5.rs
@@ -22,14 +22,12 @@
 // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::error;
 use std::fmt;
 use std::num::ParseIntError;
 
 // TODO: update the return type of `main()` to make this compile.
-fn main() -> Result<(), Box<dyn ???>> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);
diff --git a/exercises/13_error_handling/errors6.rs b/exercises/13_error_handling/errors6.rs
index aaf0948e..859d29ce 100644
--- a/exercises/13_error_handling/errors6.rs
+++ b/exercises/13_error_handling/errors6.rs
@@ -9,8 +9,6 @@
 // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 // This is a custom error type that we will be using in `parse_pos_nonzero()`.
@@ -25,13 +23,15 @@ impl ParsePosNonzeroError {
         ParsePosNonzeroError::Creation(err)
     }
     // TODO: add another error conversion function here.
-    // fn from_parseint...
+    fn from_parseint(err: ParseIntError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::ParseInt(err)
+    }
 }
 
 fn parse_pos_nonzero(s: &str) -> Result<PositiveNonzeroInteger, ParsePosNonzeroError> {
     // TODO: change this to return an appropriate error instead of panicking
     // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
+    let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parseint)?;
     PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
 }
 
diff --git a/exercises/14_generics/generics1.rs b/exercises/14_generics/generics1.rs
index 35c1d2fe..1f4fa4ac 100644
--- a/exercises/14_generics/generics1.rs
+++ b/exercises/14_generics/generics1.rs
@@ -6,9 +6,7 @@
 // Execute `rustlings hint generics1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&str> = Vec::new();
     shopping_list.push("milk");
 }
diff --git a/exercises/14_generics/generics2.rs b/exercises/14_generics/generics2.rs
index 074cd938..b0cc651f 100644
--- a/exercises/14_generics/generics2.rs
+++ b/exercises/14_generics/generics2.rs
@@ -6,14 +6,12 @@
 // Execute `rustlings hint generics2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-struct Wrapper {
-    value: u32,
+struct Wrapper<T> {
+    value: T,
 }
 
-impl Wrapper {
-    pub fn new(value: u32) -> Self {
+impl<T> Wrapper<T> {
+    pub fn new(value: T) -> Self {
         Wrapper { value }
     }
 }
diff --git a/exercises/15_traits/traits1.rs b/exercises/15_traits/traits1.rs
index 37dfcbfe..723660ad 100644
--- a/exercises/15_traits/traits1.rs
+++ b/exercises/15_traits/traits1.rs
@@ -7,14 +7,15 @@
 // Execute `rustlings hint traits1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
 impl AppendBar for String {
     // TODO: Implement `AppendBar` for type `String`.
+    fn append_bar(self) -> Self {
+        format!("{self}Bar")
+    }
 }
 
 fn main() {
diff --git a/exercises/15_traits/traits2.rs b/exercises/15_traits/traits2.rs
index 3e35f8e1..6d354993 100644
--- a/exercises/15_traits/traits2.rs
+++ b/exercises/15_traits/traits2.rs
@@ -8,12 +8,17 @@
 //
 // Execute `rustlings hint traits2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
+impl AppendBar for Vec<String> {
+    fn append_bar(mut self) -> Self {
+        self.push(String::from("Bar"));
+        self
+    }
+}
+
 // TODO: Implement trait `AppendBar` for a vector of strings.
 
 #[cfg(test)]
diff --git a/exercises/15_traits/traits3.rs b/exercises/15_traits/traits3.rs
index 4e2b06b0..7b758747 100644
--- a/exercises/15_traits/traits3.rs
+++ b/exercises/15_traits/traits3.rs
@@ -8,10 +8,10 @@
 // Execute `rustlings hint traits3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub trait Licensed {
-    fn licensing_info(&self) -> String;
+    fn licensing_info(&self) -> String {
+        String::from("Some information")
+    }
 }
 
 struct SomeSoftware {
diff --git a/exercises/15_traits/traits4.rs b/exercises/15_traits/traits4.rs
index 4bda3e57..4f3e19dc 100644
--- a/exercises/15_traits/traits4.rs
+++ b/exercises/15_traits/traits4.rs
@@ -7,8 +7,6 @@
 // Execute `rustlings hint traits4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub trait Licensed {
     fn licensing_info(&self) -> String {
         "some information".to_string()
@@ -23,7 +21,7 @@ impl Licensed for SomeSoftware {}
 impl Licensed for OtherSoftware {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn compare_license_types(software: ??, software_two: ??) -> bool {
+fn compare_license_types(software: impl Licensed, software_two: impl Licensed) -> bool {
     software.licensing_info() == software_two.licensing_info()
 }
 
diff --git a/exercises/15_traits/traits5.rs b/exercises/15_traits/traits5.rs
index df183805..07bb2068 100644
--- a/exercises/15_traits/traits5.rs
+++ b/exercises/15_traits/traits5.rs
@@ -7,8 +7,6 @@
 // Execute `rustlings hint traits5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub trait SomeTrait {
     fn some_function(&self) -> bool {
         true
@@ -30,7 +28,7 @@ impl SomeTrait for OtherStruct {}
 impl OtherTrait for OtherStruct {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn some_func(item: ??) -> bool {
+fn some_func(item: impl SomeTrait + OtherTrait) -> bool {
     item.some_function() && item.other_function()
 }
 
diff --git a/exercises/16_lifetimes/lifetimes1.rs b/exercises/16_lifetimes/lifetimes1.rs
index 87bde490..5fe45ae0 100644
--- a/exercises/16_lifetimes/lifetimes1.rs
+++ b/exercises/16_lifetimes/lifetimes1.rs
@@ -8,9 +8,7 @@
 // Execute `rustlings hint lifetimes1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-fn longest(x: &str, y: &str) -> &str {
+fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
     if x.len() > y.len() {
         x
     } else {
diff --git a/exercises/16_lifetimes/lifetimes2.rs b/exercises/16_lifetimes/lifetimes2.rs
index 4f3d8c18..46c3c335 100644
--- a/exercises/16_lifetimes/lifetimes2.rs
+++ b/exercises/16_lifetimes/lifetimes2.rs
@@ -6,8 +6,6 @@
 // Execute `rustlings hint lifetimes2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
     if x.len() > y.len() {
         x
@@ -18,9 +16,9 @@ fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
 
 fn main() {
     let string1 = String::from("long string is long");
+    let string2 = String::from("xyz");
     let result;
     {
-        let string2 = String::from("xyz");
         result = longest(string1.as_str(), string2.as_str());
     }
     println!("The longest string is '{}'", result);
diff --git a/exercises/16_lifetimes/lifetimes3.rs b/exercises/16_lifetimes/lifetimes3.rs
index 9c59f9c0..aede10de 100644
--- a/exercises/16_lifetimes/lifetimes3.rs
+++ b/exercises/16_lifetimes/lifetimes3.rs
@@ -5,11 +5,9 @@
 // Execute `rustlings hint lifetimes3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-struct Book {
-    author: &str,
-    title: &str,
+struct Book<'a> {
+    author: &'a str,
+    title: &'a str,
 }
 
 fn main() {
diff --git a/exercises/17_tests/tests1.rs b/exercises/17_tests/tests1.rs
index 810277ac..eab3ba7a 100644
--- a/exercises/17_tests/tests1.rs
+++ b/exercises/17_tests/tests1.rs
@@ -10,12 +10,10 @@
 // Execute `rustlings hint tests1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert() {
-        assert!();
+        assert!(true);
     }
 }
diff --git a/exercises/17_tests/tests2.rs b/exercises/17_tests/tests2.rs
index f8024e9f..ed6b4967 100644
--- a/exercises/17_tests/tests2.rs
+++ b/exercises/17_tests/tests2.rs
@@ -6,12 +6,10 @@
 // Execute `rustlings hint tests2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert_eq() {
-        assert_eq!();
+        assert_eq!(1, 1);
     }
 }
diff --git a/exercises/17_tests/tests3.rs b/exercises/17_tests/tests3.rs
index 4013e384..073fb32a 100644
--- a/exercises/17_tests/tests3.rs
+++ b/exercises/17_tests/tests3.rs
@@ -7,8 +7,6 @@
 // Execute `rustlings hint tests3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub fn is_even(num: i32) -> bool {
     num % 2 == 0
 }
@@ -19,11 +17,11 @@ mod tests {
 
     #[test]
     fn is_true_when_even() {
-        assert!();
+        assert!(is_even(2));
     }
 
     #[test]
     fn is_false_when_odd() {
-        assert!();
+        assert!(!is_even(5));
     }
 }
diff --git a/exercises/17_tests/tests4.rs b/exercises/17_tests/tests4.rs
index 935d0db1..57dbc530 100644
--- a/exercises/17_tests/tests4.rs
+++ b/exercises/17_tests/tests4.rs
@@ -5,8 +5,6 @@
 // Execute `rustlings hint tests4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 struct Rectangle {
     width: i32,
     height: i32
@@ -30,17 +28,19 @@ mod tests {
     fn correct_width_and_height() {
         // This test should check if the rectangle is the size that we pass into its constructor
         let rect = Rectangle::new(10, 20);
-        assert_eq!(???, 10); // check width
-        assert_eq!(???, 20); // check height
+        assert_eq!(rect.width, 10); // check width
+        assert_eq!(rect.height, 20); // check height
     }
 
     #[test]
+    #[should_panic]
     fn negative_width() {
         // This test should check if program panics when we try to create rectangle with negative width
         let _rect = Rectangle::new(-10, 10);
     }
 
     #[test]
+    #[should_panic]
     fn negative_height() {
         // This test should check if program panics when we try to create rectangle with negative height
         let _rect = Rectangle::new(10, -10);
diff --git a/exercises/18_iterators/iterators1.rs b/exercises/18_iterators/iterators1.rs
index 31076bb9..def01d84 100644
--- a/exercises/18_iterators/iterators1.rs
+++ b/exercises/18_iterators/iterators1.rs
@@ -9,18 +9,16 @@
 // Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
 
-    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1
+    let mut my_iterable_fav_fruits = my_fav_fruits.iter();   // TODO: Step 1
 
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"custard apple"));     // TODO: Step 2
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach"));     // TODO: Step 3
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 4
+    assert_eq!(my_iterable_fav_fruits.next(), None);     // TODO: Step 4
 }
diff --git a/exercises/18_iterators/iterators2.rs b/exercises/18_iterators/iterators2.rs
index dda82a08..05b4f01e 100644
--- a/exercises/18_iterators/iterators2.rs
+++ b/exercises/18_iterators/iterators2.rs
@@ -6,8 +6,6 @@
 // Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 // Step 1.
 // Complete the `capitalize_first` function.
 // "hello" -> "Hello"
@@ -15,7 +13,7 @@ pub fn capitalize_first(input: &str) -> String {
     let mut c = input.chars();
     match c.next() {
         None => String::new(),
-        Some(first) => ???,
+        Some(first) => format!("{}{}", first.to_ascii_uppercase(), c.as_str())
     }
 }
 
@@ -24,7 +22,10 @@ pub fn capitalize_first(input: &str) -> String {
 // Return a vector of strings.
 // ["hello", "world"] -> ["Hello", "World"]
 pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
-    vec![]
+    words
+        .iter()
+        .map(|&w| capitalize_first(&w[..]))
+        .collect()
 }
 
 // Step 3.
@@ -32,7 +33,10 @@ pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
 // Return a single string.
 // ["hello", " ", "world"] -> "Hello World"
 pub fn capitalize_words_string(words: &[&str]) -> String {
-    String::new()
+    words
+        .iter()
+        .map(|&w| capitalize_first(&w[..]))
+        .collect()
 }
 
 #[cfg(test)]
diff --git a/exercises/18_iterators/iterators3.rs b/exercises/18_iterators/iterators3.rs
index 29fa23a3..30ab565e 100644
--- a/exercises/18_iterators/iterators3.rs
+++ b/exercises/18_iterators/iterators3.rs
@@ -9,8 +9,6 @@
 // Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug, PartialEq, Eq)]
 pub enum DivisionError {
     NotDivisible(NotDivisibleError),
@@ -26,23 +24,31 @@ pub struct NotDivisibleError {
 // Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
 // Otherwise, return a suitable error.
 pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
-    todo!();
+    if b == 0 {
+        Err(DivisionError::DivideByZero)
+    } else if a % b > 0 {
+        Err(DivisionError::NotDivisible(NotDivisibleError { dividend: a, divisor: b }))
+    } else {
+        Ok(a / b)
+    }
 }
 
 // Complete the function and return a value of the correct type so the test
 // passes.
 // Desired output: Ok([1, 11, 1426, 3])
-fn result_with_list() -> () {
+fn result_with_list() -> Result<Vec<i32>, DivisionError> {
     let numbers = vec![27, 297, 38502, 81];
-    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    let division_results = numbers.into_iter().map(|n| divide(n, 27)).collect();
+    division_results
 }
 
 // Complete the function and return a value of the correct type so the test
 // passes.
 // Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
-fn list_of_results() -> () {
+fn list_of_results() -> Vec<Result<i32, DivisionError>> {
     let numbers = vec![27, 297, 38502, 81];
-    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    let division_results = numbers.into_iter().map(|n| divide(n, 27)).collect();
+    division_results
 }
 
 #[cfg(test)]
diff --git a/exercises/18_iterators/iterators4.rs b/exercises/18_iterators/iterators4.rs
index 79e1692b..02bae334 100644
--- a/exercises/18_iterators/iterators4.rs
+++ b/exercises/18_iterators/iterators4.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub fn factorial(num: u64) -> u64 {
     // Complete this function to return the factorial of num
     // Do not use:
@@ -15,6 +13,7 @@ pub fn factorial(num: u64) -> u64 {
     // For an extra challenge, don't use:
     // - recursion
     // Execute `rustlings hint iterators4` for hints.
+    (1..num+1).fold(1, |acc, n| acc * n )
 }
 
 #[cfg(test)]
diff --git a/exercises/18_iterators/iterators5.rs b/exercises/18_iterators/iterators5.rs
index a062ee4c..21e34b1f 100644
--- a/exercises/18_iterators/iterators5.rs
+++ b/exercises/18_iterators/iterators5.rs
@@ -11,8 +11,6 @@
 // Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(Clone, Copy, PartialEq, Eq)]
@@ -35,7 +33,7 @@ fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
 fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
     // map is a hashmap with String keys and Progress values.
     // map = { "variables1": Complete, "from_str": None, ... }
-    todo!();
+    map.iter().filter(|(k, v)| **v == value).count()
 }
 
 fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
@@ -54,7 +52,7 @@ fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Pr
     // collection is a slice of hashmaps.
     // collection = [{ "variables1": Complete, "from_str": None, ... },
     //     { "variables2": Complete, ... }, ... ]
-    todo!();
+    collection.iter().map(|map| count_iterator(map, value)).sum()
 }
 
 #[cfg(test)]
diff --git a/exercises/19_smart_pointers/arc1.rs b/exercises/19_smart_pointers/arc1.rs
index 3526ddcb..418616f7 100644
--- a/exercises/19_smart_pointers/arc1.rs
+++ b/exercises/19_smart_pointers/arc1.rs
@@ -21,19 +21,17 @@
 //
 // Execute `rustlings hint arc1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #![forbid(unused_imports)] // Do not change this, (or the next) line.
 use std::sync::Arc;
 use std::thread;
 
 fn main() {
     let numbers: Vec<_> = (0..100u32).collect();
-    let shared_numbers = // TODO
+    let shared_numbers = Arc::new(numbers);
     let mut joinhandles = Vec::new();
 
     for offset in 0..8 {
-        let child_numbers = // TODO
+        let child_numbers = Arc::clone(&shared_numbers);
         joinhandles.push(thread::spawn(move || {
             let sum: u32 = child_numbers.iter().filter(|&&n| n % 8 == offset).sum();
             println!("Sum of offset {} is {}", offset, sum);
diff --git a/exercises/19_smart_pointers/box1.rs b/exercises/19_smart_pointers/box1.rs
index 513e7daa..71733f61 100644
--- a/exercises/19_smart_pointers/box1.rs
+++ b/exercises/19_smart_pointers/box1.rs
@@ -18,11 +18,9 @@
 //
 // Execute `rustlings hint box1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 pub enum List {
-    Cons(i32, List),
+    Cons(i32, Box<List>),
     Nil,
 }
 
@@ -35,11 +33,11 @@ fn main() {
 }
 
 pub fn create_empty_list() -> List {
-    todo!()
+    List::Nil
 }
 
 pub fn create_non_empty_list() -> List {
-    todo!()
+    List::Cons(1, Box::new(List::Nil))
 }
 
 #[cfg(test)]
diff --git a/exercises/19_smart_pointers/cow1.rs b/exercises/19_smart_pointers/cow1.rs
index fcd3e0bb..f3a5987e 100644
--- a/exercises/19_smart_pointers/cow1.rs
+++ b/exercises/19_smart_pointers/cow1.rs
@@ -12,8 +12,6 @@
 //
 // Execute `rustlings hint cow1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::borrow::Cow;
 
 fn abs_all<'a, 'b>(input: &'a mut Cow<'b, [i32]>) -> &'a mut Cow<'b, [i32]> {
@@ -49,6 +47,8 @@ mod tests {
         let mut input = Cow::from(&slice[..]);
         match abs_all(&mut input) {
             // TODO
+            Cow::Borrowed(_) => Ok(()),
+            _ => Err("Expected borrowed value"),
         }
     }
 
@@ -61,6 +61,8 @@ mod tests {
         let mut input = Cow::from(slice);
         match abs_all(&mut input) {
             // TODO
+            Cow::Owned(_) => Ok(()),
+            _ => Err("Expected owned value"),
         }
     }
 
@@ -73,6 +75,8 @@ mod tests {
         let mut input = Cow::from(slice);
         match abs_all(&mut input) {
             // TODO
+            Cow::Owned(_) => Ok(()),
+            _ => Err("Expected owned value")
         }
     }
 }
diff --git a/exercises/19_smart_pointers/rc1.rs b/exercises/19_smart_pointers/rc1.rs
index 1b903469..2373657e 100644
--- a/exercises/19_smart_pointers/rc1.rs
+++ b/exercises/19_smart_pointers/rc1.rs
@@ -10,8 +10,6 @@
 //
 // Execute `rustlings hint rc1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::rc::Rc;
 
 #[derive(Debug)]
@@ -61,17 +59,17 @@ fn main() {
     jupiter.details();
 
     // TODO
-    let saturn = Planet::Saturn(Rc::new(Sun {}));
+    let saturn = Planet::Saturn(Rc::clone(&sun));
     println!("reference count = {}", Rc::strong_count(&sun)); // 7 references
     saturn.details();
 
     // TODO
-    let uranus = Planet::Uranus(Rc::new(Sun {}));
+    let uranus = Planet::Uranus(Rc::clone(&sun));
     println!("reference count = {}", Rc::strong_count(&sun)); // 8 references
     uranus.details();
 
     // TODO
-    let neptune = Planet::Neptune(Rc::new(Sun {}));
+    let neptune = Planet::Neptune(Rc::clone(&sun));
     println!("reference count = {}", Rc::strong_count(&sun)); // 9 references
     neptune.details();
 
@@ -93,12 +91,15 @@ fn main() {
     println!("reference count = {}", Rc::strong_count(&sun)); // 4 references
 
     // TODO
+    drop(earth);
     println!("reference count = {}", Rc::strong_count(&sun)); // 3 references
 
     // TODO
+    drop(venus);
     println!("reference count = {}", Rc::strong_count(&sun)); // 2 references
 
     // TODO
+    drop(mercury);
     println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference
 
     assert_eq!(Rc::strong_count(&sun), 1);
diff --git a/exercises/20_threads/threads1.rs b/exercises/20_threads/threads1.rs
index 80b6def3..34c54d24 100644
--- a/exercises/20_threads/threads1.rs
+++ b/exercises/20_threads/threads1.rs
@@ -8,8 +8,6 @@
 // Execute `rustlings hint threads1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::thread;
 use std::time::{Duration, Instant};
 
@@ -27,6 +25,7 @@ fn main() {
     let mut results: Vec<u128> = vec![];
     for handle in handles {
         // TODO: a struct is returned from thread::spawn, can you use it?
+        results.push(handle.join().unwrap());
     }
 
     if results.len() != 10 {
diff --git a/exercises/20_threads/threads2.rs b/exercises/20_threads/threads2.rs
index 62dad80d..ec5c61b2 100644
--- a/exercises/20_threads/threads2.rs
+++ b/exercises/20_threads/threads2.rs
@@ -7,9 +7,7 @@
 // Execute `rustlings hint threads2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
 
@@ -18,14 +16,14 @@ struct JobStatus {
 }
 
 fn main() {
-    let status = Arc::new(JobStatus { jobs_completed: 0 });
+    let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));
     let mut handles = vec![];
     for _ in 0..10 {
         let status_shared = Arc::clone(&status);
         let handle = thread::spawn(move || {
             thread::sleep(Duration::from_millis(250));
             // TODO: You must take an action before you update a shared value
-            status_shared.jobs_completed += 1;
+            status_shared.lock().unwrap().jobs_completed += 1;
         });
         handles.push(handle);
     }
@@ -34,6 +32,6 @@ fn main() {
         // TODO: Print the value of the JobStatus.jobs_completed. Did you notice
         // anything interesting in the output? Do you have to 'join' on all the
         // handles?
-        println!("jobs completed {}", ???);
+        println!("jobs completed {}", status.lock().unwrap().jobs_completed);
     }
 }
diff --git a/exercises/20_threads/threads3.rs b/exercises/20_threads/threads3.rs
index 91006bbc..1aa54e2a 100644
--- a/exercises/20_threads/threads3.rs
+++ b/exercises/20_threads/threads3.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint threads3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::sync::mpsc;
 use std::sync::Arc;
 use std::thread;
@@ -30,11 +28,12 @@ fn send_tx(q: Queue, tx: mpsc::Sender<u32>) -> () {
     let qc = Arc::new(q);
     let qc1 = Arc::clone(&qc);
     let qc2 = Arc::clone(&qc);
+    let tx1 = tx.clone();
 
     thread::spawn(move || {
         for val in &qc1.first_half {
             println!("sending {:?}", val);
-            tx.send(*val).unwrap();
+            tx1.send(*val).unwrap();
             thread::sleep(Duration::from_secs(1));
         }
     });
diff --git a/exercises/21_macros/macros1.rs b/exercises/21_macros/macros1.rs
index 678de6ee..9d0edee3 100644
--- a/exercises/21_macros/macros1.rs
+++ b/exercises/21_macros/macros1.rs
@@ -3,8 +3,6 @@
 // Execute `rustlings hint macros1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
@@ -12,5 +10,5 @@ macro_rules! my_macro {
 }
 
 fn main() {
-    my_macro();
+    my_macro!();
 }
diff --git a/exercises/21_macros/macros2.rs b/exercises/21_macros/macros2.rs
index 788fc16a..a87be198 100644
--- a/exercises/21_macros/macros2.rs
+++ b/exercises/21_macros/macros2.rs
@@ -3,14 +3,12 @@
 // Execute `rustlings hint macros2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-fn main() {
-    my_macro!();
-}
-
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
     };
 }
+
+fn main() {
+    my_macro!();
+}
diff --git a/exercises/21_macros/macros3.rs b/exercises/21_macros/macros3.rs
index b795c149..b5be9c39 100644
--- a/exercises/21_macros/macros3.rs
+++ b/exercises/21_macros/macros3.rs
@@ -5,8 +5,7 @@
 // Execute `rustlings hint macros3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
+#[macro_use]
 mod macros {
     macro_rules! my_macro {
         () => {
diff --git a/exercises/21_macros/macros4.rs b/exercises/21_macros/macros4.rs
index 71b45a09..45d80235 100644
--- a/exercises/21_macros/macros4.rs
+++ b/exercises/21_macros/macros4.rs
@@ -3,13 +3,11 @@
 // Execute `rustlings hint macros4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[rustfmt::skip]
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
-    }
+    };
     ($val:expr) => {
         println!("Look at this other macro: {}", $val);
     }
diff --git a/exercises/22_clippy/clippy1.rs b/exercises/22_clippy/clippy1.rs
index 95c0141f..e2b1ebf4 100644
--- a/exercises/22_clippy/clippy1.rs
+++ b/exercises/22_clippy/clippy1.rs
@@ -9,12 +9,10 @@
 // Execute `rustlings hint clippy1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::f32;
 
 fn main() {
-    let pi = 3.14f32;
+    let pi = f32::consts::PI;
     let radius = 5.00f32;
 
     let area = pi * f32::powi(radius, 2);
diff --git a/exercises/22_clippy/clippy2.rs b/exercises/22_clippy/clippy2.rs
index 9b87a0b7..79c5c9fe 100644
--- a/exercises/22_clippy/clippy2.rs
+++ b/exercises/22_clippy/clippy2.rs
@@ -3,12 +3,10 @@
 // Execute `rustlings hint clippy2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let mut res = 42;
     let option = Some(12);
-    for x in option {
+    if let Some(x) = option {
         res += x;
     }
     println!("{}", res);
diff --git a/exercises/22_clippy/clippy3.rs b/exercises/22_clippy/clippy3.rs
index 5a95f5b8..fa5900cb 100644
--- a/exercises/22_clippy/clippy3.rs
+++ b/exercises/22_clippy/clippy3.rs
@@ -3,28 +3,27 @@
 // Here's a couple more easy Clippy fixes, so you can see its utility.
 // No hints.
 
-// I AM NOT DONE
-
 #[allow(unused_variables, unused_assignments)]
 fn main() {
-    let my_option: Option<()> = None;
-    if my_option.is_none() {
-        my_option.unwrap();
-    }
+    // let my_option: Option<()> = None;
+    // if my_option.is_none() {
+    //     my_option.unwrap();
+    // }
 
     let my_arr = &[
-        -1, -2, -3
+        -1, -2, -3,
         -4, -5, -6
     ];
     println!("My array! Here it is: {:?}", my_arr);
 
-    let my_empty_vec = vec![1, 2, 3, 4, 5].resize(0, 5);
-    println!("This Vec is empty, see? {:?}", my_empty_vec);
+    // let my_empty_vec = vec![1, 2, 3, 4, 5].resize(0, 5);
+    // println!("This Vec is empty, see? {:?}", my_empty_vec);
 
     let mut value_a = 45;
     let mut value_b = 66;
     // Let's swap these two!
-    value_a = value_b;
-    value_b = value_a;
+    // value_a = value_b;
+    // value_b = value_a;
+    std::mem::swap(&mut value_a, &mut value_b);
     println!("value a: {}; value b: {}", value_a, value_b);
 }
diff --git a/exercises/23_conversions/as_ref_mut.rs b/exercises/23_conversions/as_ref_mut.rs
index 2ba9e3f0..f509d6fd 100644
--- a/exercises/23_conversions/as_ref_mut.rs
+++ b/exercises/23_conversions/as_ref_mut.rs
@@ -7,25 +7,23 @@
 // Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 // Obtain the number of bytes (not characters) in the given argument.
 // TODO: Add the AsRef trait appropriately as a trait bound.
-fn byte_counter<T>(arg: T) -> usize {
+fn byte_counter<T: AsRef<str>>(arg: T) -> usize {
     arg.as_ref().as_bytes().len()
 }
 
 // Obtain the number of characters (not bytes) in the given argument.
 // TODO: Add the AsRef trait appropriately as a trait bound.
-fn char_counter<T>(arg: T) -> usize {
+fn char_counter<T: AsRef<str>>(arg: T) -> usize {
     arg.as_ref().chars().count()
 }
 
 // Squares a number using as_mut().
 // TODO: Add the appropriate trait bound.
-fn num_sq<T>(arg: &mut T) {
+fn num_sq<T: AsMut<u32>>(arg: &mut T) {
     // TODO: Implement the function body.
-    ???
+    *arg.as_mut() = *arg.as_mut() * *arg.as_mut();
 }
 
 #[cfg(test)]
diff --git a/exercises/23_conversions/from_into.rs b/exercises/23_conversions/from_into.rs
index 60911f3e..91d11bcf 100644
--- a/exercises/23_conversions/from_into.rs
+++ b/exercises/23_conversions/from_into.rs
@@ -40,10 +40,28 @@ impl Default for Person {
 // If while parsing the age, something goes wrong, then return the default of
 // Person Otherwise, then return an instantiated Person object with the results
 
-// I AM NOT DONE
-
 impl From<&str> for Person {
     fn from(s: &str) -> Person {
+        match s.len() {
+            0 => Person::default(),
+            _ => {
+                let mut s_iter = s.split(",");
+                match s_iter.next() {
+                    Some("") => Person::default(),
+                    Some(name) => match s_iter.next() {
+                        Some(age_str) => match age_str.parse::<usize>() {
+                            Ok(age) => Person {
+                                name: String::from(name),
+                                age,
+                            },
+                            _ => Person::default(),
+                        },
+                        None => Person::default(),
+                    },
+                    None => Person::default(),
+                }
+            }
+        }
     }
 }
 
diff --git a/exercises/23_conversions/from_str.rs b/exercises/23_conversions/from_str.rs
index 34472c32..af870544 100644
--- a/exercises/23_conversions/from_str.rs
+++ b/exercises/23_conversions/from_str.rs
@@ -31,8 +31,6 @@ enum ParsePersonError {
     ParseInt(ParseIntError),
 }
 
-// I AM NOT DONE
-
 // Steps:
 // 1. If the length of the provided string is 0, an error should be returned
 // 2. Split the given string on the commas present in it
@@ -52,6 +50,52 @@ enum ParsePersonError {
 impl FromStr for Person {
     type Err = ParsePersonError;
     fn from_str(s: &str) -> Result<Person, Self::Err> {
+        if s.len() == 0 {
+            return Err(ParsePersonError::Empty);
+        }
+
+        let mut s_iter = s.split(",");
+
+        if s_iter.clone().count() != 2 {
+            return Err(ParsePersonError::BadLen);
+        }
+
+        match s_iter.next().ok_or(ParsePersonError::NoName)? {
+            "" => Err(ParsePersonError::NoName),
+            name => {
+                let age_str = s_iter.next().ok_or(ParsePersonError::Empty)?;
+                let age = age_str
+                    .parse::<usize>()
+                    .map_err(|err| ParsePersonError::ParseInt(err))?;
+
+                Ok(Person {
+                    name: name.to_string(),
+                    age,
+                })
+            }
+        }
+
+        // if s.len() > 0 {
+        //     let mut s_iter = s.split(",");
+
+        //     if s_iter.clone().count() == 2 {
+        //         match s_iter.next() {
+        //             Some("") => Err(ParsePersonError::NoName),
+        //             Some(name) => match s_iter.next().unwrap().parse::<usize>() {
+        //                 Ok(age) => Ok(Person {
+        //                     name: name.to_string(),
+        //                     age,
+        //                 }),
+        //                 Err(err) => Err(ParsePersonError::ParseInt(err)),
+        //             },
+        //             None => Err(ParsePersonError::NoName),
+        //         }
+        //     } else {
+        //         Err(ParsePersonError::BadLen)
+        //     }
+        // } else {
+        //     Err(ParsePersonError::Empty)
+        // }
     }
 }
 
diff --git a/exercises/23_conversions/try_from_into.rs b/exercises/23_conversions/try_from_into.rs
index 32d6ef39..5b0cbe8d 100644
--- a/exercises/23_conversions/try_from_into.rs
+++ b/exercises/23_conversions/try_from_into.rs
@@ -27,8 +27,6 @@ enum IntoColorError {
     IntConversion,
 }
 
-// I AM NOT DONE
-
 // Your task is to complete this implementation and return an Ok result of inner
 // type Color. You need to create an implementation for a tuple of three
 // integers, an array of three integers, and a slice of integers.
@@ -41,6 +39,16 @@ enum IntoColorError {
 impl TryFrom<(i16, i16, i16)> for Color {
     type Error = IntoColorError;
     fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
+        let rgb_range = 0..256;
+        let (r, g, b)  = tuple;
+
+        for rgb in [r, g, b].iter() {
+            if !rgb_range.contains(rgb) {
+                return Err(IntoColorError::IntConversion)
+            }
+        }
+        
+        Ok(Color { red: r as u8, green: g as u8, blue: b as u8 })
     }
 }
 
@@ -48,6 +56,17 @@ impl TryFrom<(i16, i16, i16)> for Color {
 impl TryFrom<[i16; 3]> for Color {
     type Error = IntoColorError;
     fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
+        let rgb_range = 0..256;
+
+        for rgb in arr.iter() {
+            if !rgb_range.contains(rgb) {
+                return Err(IntoColorError::IntConversion)
+            }
+        }
+
+        let [r, g, b] = arr;
+        
+        Ok(Color { red: r as u8, green: g as u8, blue: b as u8})
     }
 }
 
@@ -55,6 +74,31 @@ impl TryFrom<[i16; 3]> for Color {
 impl TryFrom<&[i16]> for Color {
     type Error = IntoColorError;
     fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
+        // if !slice.clone().into_iter().count() == 3 {
+        //     return Err(IntoColorError::BadLen)
+        // }
+        // 
+        // let rgb_range = 0..256;
+        // 
+        // for rgb in slice.iter() {
+        //     if !rgb_range.contains(rgb) {
+        //         return Err(IntoColorError::IntConversion)
+        //     }
+        // }
+        //
+        // Ok(Color { red: *r as u8, green: *g as u8, blue: *b as u8})
+
+        let [r, g, b] = slice else {
+            return Err(IntoColorError::BadLen)
+        };
+
+        let mut array: [i16; 3] = [0; 3];
+
+        array[0] = slice[0];
+        array[1] = slice[1];
+        array[2] = slice[2];
+
+        Self::try_from(array)
     }
 }
 
diff --git a/exercises/23_conversions/using_as.rs b/exercises/23_conversions/using_as.rs
index 414cef3a..a9f1e449 100644
--- a/exercises/23_conversions/using_as.rs
+++ b/exercises/23_conversions/using_as.rs
@@ -10,11 +10,9 @@
 // Execute `rustlings hint using_as` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn average(values: &[f64]) -> f64 {
     let total = values.iter().sum::<f64>();
-    total / values.len()
+    total / values.len() as f64
 }
 
 fn main() {
diff --git a/exercises/quiz1.rs b/exercises/quiz1.rs
index 4ee5ada7..5ed76a5f 100644
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -13,10 +13,14 @@
 //
 // No hints this time ;)
 
-// I AM NOT DONE
-
 // Put your function here!
-// fn calculate_price_of_apples {
+fn calculate_price_of_apples(quantity: i32) -> i32 {
+    if (quantity < 41) {
+        quantity * 2
+    } else {
+        quantity
+    }
+}
 
 // Don't modify this function!
 #[test]
diff --git a/exercises/quiz2.rs b/exercises/quiz2.rs
index 29925caf..2e00dcee 100644
--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -20,8 +20,6 @@
 //
 // No hints this time!
 
-// I AM NOT DONE
-
 pub enum Command {
     Uppercase,
     Trim,
@@ -32,11 +30,16 @@ mod my_module {
     use super::Command;
 
     // TODO: Complete the function signature!
-    pub fn transformer(input: ???) -> ??? {
+    pub fn transformer(input: Vec<(&str, Command)>) -> Vec<String> {
         // TODO: Complete the output declaration!
-        let mut output: ??? = vec![];
+        let mut output: Vec<String> = vec![];
         for (string, command) in input.iter() {
             // TODO: Complete the function body. You can do it!
+            output.push(match command {
+                Command::Uppercase => string.to_uppercase(),
+                Command::Trim => string.trim().to_string(),
+                Command::Append(n) => format!("{string}{}", "bar".repeat(*n))
+            });
         }
         output
     }
@@ -45,7 +48,7 @@ mod my_module {
 #[cfg(test)]
 mod tests {
     // TODO: What do we need to import to have `transformer` in scope?
-    use ???;
+    use crate::my_module::transformer;
     use super::Command;
 
     #[test]
diff --git a/exercises/quiz3.rs b/exercises/quiz3.rs
index 3b01d313..3ecfbe2b 100644
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -16,18 +16,20 @@
 //
 // Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+use std::fmt::Display;
 
-pub struct ReportCard {
-    pub grade: f32,
+pub struct ReportCard<T> {
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T: Display> ReportCard<T> {
     pub fn print(&self) -> String {
-        format!("{} ({}) - achieved a grade of {}",
-            &self.student_name, &self.student_age, &self.grade)
+        format!(
+            "{} ({}) - achieved a grade of {}",
+            &self.student_name, &self.student_age, &self.grade
+        )
     }
 }
 
@@ -52,7 +54,7 @@ mod tests {
     fn generate_alphabetic_report_card() {
         // TODO: Make sure to change the grade here after you finish the exercise.
         let report_card = ReportCard {
-            grade: 2.1,
+            grade: "A+".to_string(),
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };