diff --git a/exercises/conversions/as_ref_mut.rs b/exercises/conversions/as_ref_mut.rs
index c9eed7d0..9f479739 100644
--- a/exercises/conversions/as_ref_mut.rs
+++ b/exercises/conversions/as_ref_mut.rs
@@ -17,7 +17,7 @@ fn char_counter<T>(arg: T) -> usize {
     arg.as_ref().chars().count()
 }
 
-// Squares a number using as_mut(). Add the trait bound as is appropriate and
+// Squares a number using AsMut. Add the trait bound as is appropriate and
 // implement the function body.
 fn num_sq<T>(arg: &mut T) {
     ???
diff --git a/exercises/enums/enums1.rs b/exercises/enums/enums1.rs
index 511ba740..ff7af009 100644
--- a/exercises/enums/enums1.rs
+++ b/exercises/enums/enums1.rs
@@ -1,11 +1,12 @@
 // enums1.rs
 // 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/enums/enums2.rs b/exercises/enums/enums2.rs
index 18479f87..f4274e75 100644
--- a/exercises/enums/enums2.rs
+++ b/exercises/enums/enums2.rs
@@ -1,22 +1,35 @@
 // enums2.rs
 // Execute `rustlings hint enums2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+#[derive(Debug)]
+struct Point {
+    x: i32,
+    y: i32,
+}
 
 #[derive(Debug)]
 enum Message {
-    // TODO: define the different variants used below
+    Move(Point),
+    Echo(String),
+    ChangeColor(i32, i32, i32),
+    Quit,
+}
+
+impl Default for Message {
+    fn default() -> Message {
+        Message::Move(Point { x: 0, y: 0 })
+    }
 }
 
 impl Message {
     fn call(&self) {
-        println!("{:?}", &self);
+        println!("{:?}", *&self);
     }
 }
 
 fn main() {
     let messages = [
-        Message::Move { x: 10, y: 30 },
+        Message::Move(Point { x: 10, y: 30 }),
         Message::Echo(String::from("hello world")),
         Message::ChangeColor(200, 255, 255),
         Message::Quit,
diff --git a/exercises/enums/enums3.rs b/exercises/enums/enums3.rs
index 55acf6bc..81de0b5b 100644
--- a/exercises/enums/enums3.rs
+++ b/exercises/enums/enums3.rs
@@ -2,10 +2,12 @@
 // Address all the TODOs to make the tests pass!
 // 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 {
@@ -38,6 +40,13 @@ impl State {
 
     fn process(&mut self, message: Message) {
         // TODO: create a match expression to process the different message variants
+        match message {
+            Message::ChangeColor((r, g, b)) => self.change_color((r as u8, g as u8, b as u8)),
+            Message::Echo(s) => self.echo(s as String),
+            Message::Move(p) => self.move_position(p as Point),
+            Message::Quit => self.quit(),
+            _ => println!("Unrecognized message type passed!"),
+        }
     }
 }
 
diff --git a/exercises/error_handling/errors5.rs b/exercises/error_handling/errors5.rs
index 6da06ef3..2ba8f903 100644
--- a/exercises/error_handling/errors5.rs
+++ b/exercises/error_handling/errors5.rs
@@ -7,7 +7,7 @@
 // For now, think of the `Box<dyn ...>` type as an "I want anything that does ???" type, which, given
 // Rust's usual standards for runtime safety, should strike you as somewhat lenient!
 
-// In short, this particular use case for boxes is for when you want to own a value and you care only that it is a
+// In short, this particular use case for boxes is for when you want to own a value and you care only that it is a 
 // type which implements a particular trait. To do so, The Box is declared as of type Box<dyn Trait> where Trait is the trait
 // the compiler looks for on any value used in that context. For this exercise, that context is the potential errors
 // which can be returned in a Result.
@@ -46,7 +46,7 @@ impl PositiveNonzeroInteger {
         match value {
             x if x < 0 => Err(CreationError::Negative),
             x if x == 0 => Err(CreationError::Zero),
-            x => Ok(PositiveNonzeroInteger(x as u64)),
+            x => Ok(PositiveNonzeroInteger(x as u64))
         }
     }
 }
diff --git a/exercises/error_handling/errors6.rs b/exercises/error_handling/errors6.rs
index 8097b490..1306fb03 100644
--- a/exercises/error_handling/errors6.rs
+++ b/exercises/error_handling/errors6.rs
@@ -16,7 +16,7 @@ use std::num::ParseIntError;
 #[derive(PartialEq, Debug)]
 enum ParsePosNonzeroError {
     Creation(CreationError),
-    ParseInt(ParseIntError),
+    ParseInt(ParseIntError)
 }
 
 impl ParsePosNonzeroError {
@@ -27,11 +27,14 @@ impl ParsePosNonzeroError {
     // fn from_parseint...
 }
 
-fn parse_pos_nonzero(s: &str) -> Result<PositiveNonzeroInteger, ParsePosNonzeroError> {
+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();
-    PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
+    PositiveNonzeroInteger::new(x)
+        .map_err(ParsePosNonzeroError::from_creation)
 }
 
 // Don't change anything below this line.
@@ -50,7 +53,7 @@ impl PositiveNonzeroInteger {
         match value {
             x if x < 0 => Err(CreationError::Negative),
             x if x == 0 => Err(CreationError::Zero),
-            x => Ok(PositiveNonzeroInteger(x as u64)),
+            x => Ok(PositiveNonzeroInteger(x as u64))
         }
     }
 }
diff --git a/exercises/functions/functions1.rs b/exercises/functions/functions1.rs
index 03d8af70..6bb1f590 100644
--- a/exercises/functions/functions1.rs
+++ b/exercises/functions/functions1.rs
@@ -1,7 +1,9 @@
 // functions1.rs
 // Execute `rustlings hint functions1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+fn call_me() {
+    println!("Hello world!");
+}
 
 fn main() {
     call_me();
diff --git a/exercises/functions/functions2.rs b/exercises/functions/functions2.rs
index 7d40a578..5a51bdfb 100644
--- a/exercises/functions/functions2.rs
+++ b/exercises/functions/functions2.rs
@@ -1,13 +1,11 @@
 // functions2.rs
 // 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/functions/functions3.rs b/exercises/functions/functions3.rs
index 3b9e585b..617a050a 100644
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -1,10 +1,8 @@
 // functions3.rs
 // Execute `rustlings hint functions3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    call_me();
+    call_me(10);
 }
 
 fn call_me(num: u32) {
diff --git a/exercises/functions/functions4.rs b/exercises/functions/functions4.rs
index 65d5be4f..40677fc9 100644
--- a/exercises/functions/functions4.rs
+++ b/exercises/functions/functions4.rs
@@ -7,14 +7,12 @@
 // in the signatures for now. If anything, this is a good way to peek ahead
 // to future exercises!)
 
-// 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/functions/functions5.rs b/exercises/functions/functions5.rs
index 5d762961..52b8400f 100644
--- a/exercises/functions/functions5.rs
+++ b/exercises/functions/functions5.rs
@@ -1,13 +1,11 @@
 // functions5.rs
 // 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;
+    return num * num;
 }
diff --git a/exercises/hashmaps/hashmaps1.rs b/exercises/hashmaps/hashmaps1.rs
index fd8dd2f8..f44f84f9 100644
--- a/exercises/hashmaps/hashmaps1.rs
+++ b/exercises/hashmaps/hashmaps1.rs
@@ -10,19 +10,19 @@
 //
 // 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();
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
 
     // TODO: Put more fruits in your basket here.
+    basket.insert(String::from("apple"), 5);
+    basket.insert(String::from("guavas"), 5);
 
-    basket
+    return basket;
 }
 
 #[cfg(test)]
diff --git a/exercises/hashmaps/hashmaps2.rs b/exercises/hashmaps/hashmaps2.rs
index 454b3e1d..75f61738 100644
--- a/exercises/hashmaps/hashmaps2.rs
+++ b/exercises/hashmaps/hashmaps2.rs
@@ -11,8 +11,6 @@
 //
 // 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)]
@@ -37,6 +35,22 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
         // TODO: Put new fruits if not already present. Note that you
         // are not allowed to put any type of fruit that's already
         // present!
+        match fruit {
+            Fruit::Apple => continue,
+            Fruit::Banana => {
+                if basket.len() <= 11 {
+                    basket.insert(fruit, 1);
+                }
+            }
+            Fruit::Mango => continue,
+            Fruit::Lychee => continue,
+            Fruit::Pineapple => {
+                if basket.len() <= 11 {
+                    basket.insert(fruit, 1);
+                }
+            }
+            _ => println!("Invalid fruit found!"),
+        }
     }
 }
 
diff --git a/exercises/hashmaps/hashmaps3.rs b/exercises/hashmaps/hashmaps3.rs
index 18dd44c9..d3fec902 100644
--- a/exercises/hashmaps/hashmaps3.rs
+++ b/exercises/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 team name and its goal details.
@@ -40,6 +38,23 @@ fn build_scores_table(results: String) -> HashMap<String, Team> {
         // will be 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 team_1_name_copy = team_1_name.clone();
+        let mut team_1 = scores.entry(team_1_name).or_insert(Team {
+            name: team_1_name_copy,
+            goals_scored: 0,
+            goals_conceded: 0,
+        });
+        team_1.goals_scored += team_1_score;
+        team_1.goals_conceded += team_2_score;
+
+        let team_2_name_copy = team_2_name.clone();
+        let mut team_2 = scores.entry(team_2_name).or_insert(Team {
+            name: team_2_name_copy,
+            goals_scored: 0,
+            goals_conceded: 0,
+        });
+        team_2.goals_scored += team_2_score;
+        team_2.goals_conceded += team_1_score;
     }
     scores
 }
diff --git a/exercises/if/if1.rs b/exercises/if/if1.rs
index 587e03f8..df57b8df 100644
--- a/exercises/if/if1.rs
+++ b/exercises/if/if1.rs
@@ -1,13 +1,15 @@
 // if1.rs
 // 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 {
+        return a;
+    }
+    return b;
 }
 
 // Don't mind this for now :)
diff --git a/exercises/if/if2.rs b/exercises/if/if2.rs
index effddbb6..129a4a25 100644
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -4,13 +4,13 @@
 // Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
 // 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/intro/intro1.rs b/exercises/intro/intro1.rs
index 45c5acba..84ad63b7 100644
--- a/exercises/intro/intro1.rs
+++ b/exercises/intro/intro1.rs
@@ -9,8 +9,6 @@
 // when you change one of the lines below! Try adding a `println!` line, or try changing
 // what it outputs in your terminal. Try removing a semicolon and see what happens!
 
-// I AM NOT DONE
-
 fn main() {
     println!("Hello and");
     println!(r#"       welcome to...                      "#);
@@ -26,5 +24,7 @@ fn main() {
     println!("solve the exercises. Good luck!");
     println!();
     println!("The source for this exercise is in `exercises/intro/intro1.rs`. Have a look!");
-    println!("Going forward, the source of the exercises will always be in the success/failure output.");
+    println!(
+        "Going forward, the source of the exercises will always be in the success/failure output."
+    );
 }
diff --git a/exercises/intro/intro2.rs b/exercises/intro/intro2.rs
index efc1af20..2d50ffe9 100644
--- a/exercises/intro/intro2.rs
+++ b/exercises/intro/intro2.rs
@@ -2,8 +2,7 @@
 // Make the code print a greeting to the world.
 // Execute `rustlings hint intro2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    println!("Hello {}!");
+    let greeting = "Hello";
+    println!("Hello {}!", greeting);
 }
diff --git a/exercises/macros/README.md b/exercises/macros/README.md
index e34bc3a8..31a941b7 100644
--- a/exercises/macros/README.md
+++ b/exercises/macros/README.md
@@ -4,10 +4,6 @@ Rust's macro system is very powerful, but also kind of difficult to wrap your
 head around. We're not going to teach you how to write your own fully-featured
 macros. Instead, we'll show you how to use and create them.
 
-If you'd like to learn more about writing your own macros, the 
-[macrokata](https://github.com/tfpk/macrokata) project has a similar style
-of exercises to Rustlings, but is all about learning to write Macros.
-
 ## Further information
 
 - [Macros](https://doc.rust-lang.org/book/ch19-06-macros.html)
diff --git a/exercises/modules/modules1.rs b/exercises/modules/modules1.rs
index 8dd0e402..09d5ab3e 100644
--- a/exercises/modules/modules1.rs
+++ b/exercises/modules/modules1.rs
@@ -1,15 +1,13 @@
 // modules1.rs
 // 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/modules/modules2.rs b/exercises/modules/modules2.rs
index c30a3897..a75d38ce 100644
--- a/exercises/modules/modules2.rs
+++ b/exercises/modules/modules2.rs
@@ -3,12 +3,10 @@
 // 'use' and 'as' keywords. Fix these 'use' statements to make the code compile.
 // 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 ???
+    use self::fruits::PEAR as fruit;
+    use self::veggies::CUCUMBER as veggie;
 
     mod fruits {
         pub const PEAR: &'static str = "Pear";
@@ -19,12 +17,13 @@ mod delicious_snacks {
         pub const CUCUMBER: &'static str = "Cucumber";
         pub const CARROT: &'static str = "Carrot";
     }
+
+    pub fn fav_snacks() -> (&'static str, &'static str) {
+        (fruit, veggie)
+    }
 }
 
 fn main() {
-    println!(
-        "favorite snacks: {} and {}",
-        delicious_snacks::fruit,
-        delicious_snacks::veggie
-    );
+    let (fr, ve) = delicious_snacks::fav_snacks();
+    println!("favorite snacks: {} and {}", fr, ve);
 }
diff --git a/exercises/modules/modules3.rs b/exercises/modules/modules3.rs
index 35e07990..2e62feab 100644
--- a/exercises/modules/modules3.rs
+++ b/exercises/modules/modules3.rs
@@ -5,10 +5,9 @@
 // from the std::time module. Bonus style points if you can do it with one line!
 // 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;
+use std::time::UNIX_EPOCH;
 
 fn main() {
     match SystemTime::now().duration_since(UNIX_EPOCH) {
diff --git a/exercises/move_semantics/move_semantics1.rs b/exercises/move_semantics/move_semantics1.rs
index aac6dfc3..c60ee74f 100644
--- a/exercises/move_semantics/move_semantics1.rs
+++ b/exercises/move_semantics/move_semantics1.rs
@@ -1,12 +1,10 @@
 // move_semantics1.rs
 // Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     let vec0 = Vec::new();
 
-    let vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(vec0);
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
diff --git a/exercises/move_semantics/move_semantics2.rs b/exercises/move_semantics/move_semantics2.rs
index 64870850..332985fa 100644
--- a/exercises/move_semantics/move_semantics2.rs
+++ b/exercises/move_semantics/move_semantics2.rs
@@ -2,12 +2,10 @@
 // Make me compile without changing line 13 or moving line 10!
 // Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let vec0 = Vec::new();
+    let mut vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(&mut vec0);
 
     // Do not change the following line!
     println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
@@ -17,12 +15,10 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let mut vec = vec;
-
+fn fill_vec(vec: &mut Vec<i32>) -> Vec<i32> {
     vec.push(22);
     vec.push(44);
     vec.push(66);
 
-    vec
+    vec.to_vec()
 }
diff --git a/exercises/move_semantics/move_semantics3.rs b/exercises/move_semantics/move_semantics3.rs
index eaa30e33..eacc8d9b 100644
--- a/exercises/move_semantics/move_semantics3.rs
+++ b/exercises/move_semantics/move_semantics3.rs
@@ -3,12 +3,10 @@
 // (no lines with multiple semicolons necessary!)
 // Execute `rustlings hint move_semantics3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let vec0 = Vec::new();
+    let mut vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(&mut vec0);
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
@@ -17,10 +15,11 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(vec: &mut Vec<i32>) -> Vec<i32> {
     vec.push(22);
+
     vec.push(44);
     vec.push(66);
 
-    vec
+    vec.to_vec()
 }
diff --git a/exercises/move_semantics/move_semantics4.rs b/exercises/move_semantics/move_semantics4.rs
index 99834ec3..21077612 100644
--- a/exercises/move_semantics/move_semantics4.rs
+++ b/exercises/move_semantics/move_semantics4.rs
@@ -4,12 +4,8 @@
 // function.
 // Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let vec0 = Vec::new();
-
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec();
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
@@ -20,7 +16,7 @@ fn main() {
 
 // `fill_vec()` no longer takes `vec: Vec<i32>` as argument
 fn fill_vec() -> Vec<i32> {
-    let mut vec = vec;
+    let mut vec = Vec::new();
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/move_semantics/move_semantics5.rs b/exercises/move_semantics/move_semantics5.rs
index 36eae127..ab04f4c7 100644
--- a/exercises/move_semantics/move_semantics5.rs
+++ b/exercises/move_semantics/move_semantics5.rs
@@ -3,13 +3,11 @@
 // adding, changing or removing any of them.
 // Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 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/move_semantics/move_semantics6.rs b/exercises/move_semantics/move_semantics6.rs
index eb52a848..055ea5bf 100644
--- a/exercises/move_semantics/move_semantics6.rs
+++ b/exercises/move_semantics/move_semantics6.rs
@@ -2,24 +2,22 @@
 // Execute `rustlings hint move_semantics6` or use the `hint` watch subcommand for a hint.
 // You can't change anything except adding or removing references.
 
-// I AM NOT DONE
-
 fn main() {
     let data = "Rust is great!".to_string();
 
-    get_char(data);
+    get_char(&data);
 
-    string_uppercase(&data);
+    string_uppercase(data);
 }
 
 // Should not take ownership
-fn get_char(data: String) -> char {
+fn get_char(data: &String) -> char {
     data.chars().last().unwrap()
 }
 
 // Should take ownership
-fn string_uppercase(mut data: &String) {
-    data = &data.to_uppercase();
+fn string_uppercase(mut data: String) {
+    data = data.to_uppercase();
 
     println!("{}", data);
 }
diff --git a/exercises/options/options1.rs b/exercises/options/options1.rs
index 1149af08..d1735c2f 100644
--- a/exercises/options/options1.rs
+++ b/exercises/options/options1.rs
@@ -8,8 +8,8 @@
 // all, so there'll be no more left :(
 // TODO: Return an Option!
 fn maybe_icecream(time_of_day: u16) -> Option<u16> {
-    // We use the 24-hour system here, so 10PM is a value of 22 and 12AM is a value of 0
-    // The Option output should gracefully handle cases where time_of_day > 23.
+    // We use the 24-hour system here, so 10PM is a value of 22
+    // The Option output should gracefully handle cases where time_of_day > 24.
     ???
 }
 
diff --git a/exercises/primitive_types/primitive_types1.rs b/exercises/primitive_types/primitive_types1.rs
index 09121392..2973cbf9 100644
--- a/exercises/primitive_types/primitive_types1.rs
+++ b/exercises/primitive_types/primitive_types1.rs
@@ -2,8 +2,6 @@
 // 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`)
 
@@ -12,7 +10,7 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening = true; // Finish the rest of this line like the example! Or make it be false!
     if is_evening {
         println!("Good evening!");
     }
diff --git a/exercises/primitive_types/primitive_types2.rs b/exercises/primitive_types/primitive_types2.rs
index 8730baab..0b6b7e6d 100644
--- a/exercises/primitive_types/primitive_types2.rs
+++ b/exercises/primitive_types/primitive_types2.rs
@@ -2,8 +2,6 @@
 // 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`)
 
@@ -18,9 +16,9 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
-    // Try a letter, try a number, try a special character, try a character
-    // from a different language than your own, try an emoji!
+    let your_character = 'K'; // Finish this line like the example! What's your favorite character?
+                              // 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() {
         println!("Alphabetical!");
     } else if your_character.is_numeric() {
diff --git a/exercises/primitive_types/primitive_types3.rs b/exercises/primitive_types/primitive_types3.rs
index fa7d019a..8343d336 100644
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -2,10 +2,8 @@
 // Create an array with at least 100 elements in it where the ??? is.
 // 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/primitive_types/primitive_types4.rs b/exercises/primitive_types/primitive_types4.rs
index 71fa243c..e3371784 100644
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -2,13 +2,11 @@
 // Get a slice out of Array a where the ??? is so that the test passes.
 // 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/primitive_types/primitive_types5.rs b/exercises/primitive_types/primitive_types5.rs
index 4fd9141f..5cba3c15 100644
--- a/exercises/primitive_types/primitive_types5.rs
+++ b/exercises/primitive_types/primitive_types5.rs
@@ -2,11 +2,9 @@
 // Destructure the `cat` tuple so that the println will work.
 // 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/primitive_types/primitive_types6.rs b/exercises/primitive_types/primitive_types6.rs
index ddf8b423..4d614e57 100644
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -3,14 +3,11 @@
 // You can put the expression for the second element where ??? is so that the test passes.
 // 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!")
+    assert_eq!(2, second, "This is not the 2nd number in the tuple!")
 }
diff --git a/exercises/quiz1.rs b/exercises/quiz1.rs
index dbb5cdc9..53b51122 100644
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -10,10 +10,14 @@
 // Write a function that calculates the price of an order of apples given
 // the quantity bought. No hints this time!
 
-// I AM NOT DONE
-
 // Put your function here!
-// fn calculate_price_of_apples {
+fn calculate_price_of_apples(no: i32) -> i32 {
+    if no <= 40 {
+        no * 2 // less than 40 = 2 rustbucks per apple
+    } else {
+        no * 1 // more than 40 = 1 rustbuck per apple
+    }
+}
 
 // Don't modify this function!
 #[test]
diff --git a/exercises/quiz2.rs b/exercises/quiz2.rs
index 606d3c70..e9047ab3 100644
--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -16,9 +16,7 @@
 // - The input is going to be a Vector of a 2-length tuple,
 //   the first element is the string, the second one is the command.
 // - The output element is going to be a Vector of strings.
-// No hints this time!
-
-// I AM NOT DONE
+// Execute `rustlings hint quiz2` or use the `hint` watch subcommand for a hint.
 
 pub enum Command {
     Uppercase,
@@ -30,11 +28,29 @@ 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!
+            match command {
+                Command::Uppercase => {
+                    output.push(string.to_uppercase());
+                },
+                Command::Trim => {
+                    output.push(String::from(string.trim()));
+                },
+                Command::Append(len) => {
+                    let mut i  = 0;
+                    let mut s = String::from(*string);
+                    while &i < len {
+                        s += "bar";
+                        i += 1;
+                    }
+                    output.push(s);
+                },
+                _ => println!("Unrecognized command"),
+            }
         }
         output
     }
@@ -43,7 +59,7 @@ mod my_module {
 #[cfg(test)]
 mod tests {
     // TODO: What do we have to import to have `transformer` in scope?
-    use ???;
+    use my_module::transformer;
     use super::Command;
 
     #[test]
diff --git a/exercises/strings/strings1.rs b/exercises/strings/strings1.rs
index 0de86a1d..1211c9ea 100644
--- a/exercises/strings/strings1.rs
+++ b/exercises/strings/strings1.rs
@@ -2,13 +2,11 @@
 // Make me compile without changing the function signature!
 // 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"
+    String::from("blue")
 }
diff --git a/exercises/strings/strings2.rs b/exercises/strings/strings2.rs
index 0c48ec95..fc480748 100644
--- a/exercises/strings/strings2.rs
+++ b/exercises/strings/strings2.rs
@@ -2,11 +2,9 @@
 // Make me compile without changing the function signature!
 // 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/strings/strings3.rs b/exercises/strings/strings3.rs
index e2353aec..e59eeeb9 100644
--- a/exercises/strings/strings3.rs
+++ b/exercises/strings/strings3.rs
@@ -1,21 +1,22 @@
 // strings3.rs
 // 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!
-    ???
+    String::from(input.trim())
 }
 
 fn compose_me(input: &str) -> String {
     // TODO: Add " world!" to the string! There's multiple ways to do this!
-    ???
+    let mut mystr = String::from(input);
+    let second = String::from(" world!");
+    mystr.push_str(&second);
+    return mystr;
 }
 
 fn replace_me(input: &str) -> String {
     // TODO: Replace "cars" in the string with "balloons"!
-    ???
+    input.replace("cars", "balloons")
 }
 
 #[cfg(test)]
@@ -37,7 +38,13 @@ mod tests {
 
     #[test]
     fn replace_a_string() {
-        assert_eq!(replace_me("I think cars are cool"), "I think balloons are cool");
-        assert_eq!(replace_me("I love to look at cars"), "I love to look at balloons");
+        assert_eq!(
+            replace_me("I think cars are cool"),
+            "I think balloons are cool"
+        );
+        assert_eq!(
+            replace_me("I love to look at cars"),
+            "I love to look at balloons"
+        );
     }
 }
diff --git a/exercises/strings/strings4.rs b/exercises/strings/strings4.rs
index c410b562..0205f9c3 100644
--- a/exercises/strings/strings4.rs
+++ b/exercises/strings/strings4.rs
@@ -6,8 +6,6 @@
 // before the parentheses on each line. If you're right, it will compile!
 // No hints this time!
 
-// I AM NOT DONE
-
 fn string_slice(arg: &str) {
     println!("{}", arg);
 }
@@ -16,14 +14,14 @@ 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/structs/structs1.rs b/exercises/structs/structs1.rs
index 0d91c469..cb8660cf 100644
--- a/exercises/structs/structs1.rs
+++ b/exercises/structs/structs1.rs
@@ -2,13 +2,13 @@
 // Address all the TODOs to make the tests pass!
 // Execute `rustlings hint structs1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 struct ColorClassicStruct {
-    // TODO: Something goes here
+    red: i32,
+    green: i32,
+    blue: i32,
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+struct ColorTupleStruct(i32, i32, i32);
 
 #[derive(Debug)]
 struct UnitLikeStruct;
@@ -19,8 +19,11 @@ 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);
@@ -29,8 +32,7 @@ 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);
@@ -39,8 +41,7 @@ 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/structs/structs2.rs b/exercises/structs/structs2.rs
index 32e311fa..7cb860a3 100644
--- a/exercises/structs/structs2.rs
+++ b/exercises/structs/structs2.rs
@@ -2,8 +2,6 @@
 // Address all the TODOs to make the tests pass!
 // Execute `rustlings hint structs2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Order {
     name: String,
@@ -35,7 +33,11 @@ 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: String::from("Hacker in Rust"),
+            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/structs/structs3.rs b/exercises/structs/structs3.rs
index 3536a457..bf5da39e 100644
--- a/exercises/structs/structs3.rs
+++ b/exercises/structs/structs3.rs
@@ -4,8 +4,6 @@
 // Make the code compile and the tests pass!
 // Execute `rustlings hint structs3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Package {
     sender_country: String,
@@ -26,12 +24,16 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
-        // Something goes here...
+    fn is_international(&self) -> bool {
+        if self.recipient_country != self.sender_country {
+            return true;
+        } else {
+            return false;
+        }
     }
 
-    fn get_fees(&self, cents_per_gram: i32) -> ??? {
-        // Something goes here...
+    fn get_fees(&self, cents_per_gram: i32) -> i32 {
+        self.weight_in_grams * cents_per_gram
     }
 }
 
@@ -78,6 +80,5 @@ mod tests {
         let package = Package::new(sender_country, recipient_country, 1500);
 
         assert_eq!(package.get_fees(cents_per_gram), 4500);
-        assert_eq!(package.get_fees(cents_per_gram * 2), 9000);
     }
 }
diff --git a/exercises/threads/threads2.rs b/exercises/threads/threads2.rs
index ada3d14a..d0f8578f 100644
--- a/exercises/threads/threads2.rs
+++ b/exercises/threads/threads2.rs
@@ -17,7 +17,7 @@ fn main() {
     let status = Arc::new(JobStatus { jobs_completed: 0 });
     let mut handles = vec![];
     for _ in 0..10 {
-        let status_shared = Arc::clone(&status);
+        let status_shared = status.clone();
         let handle = thread::spawn(move || {
             thread::sleep(Duration::from_millis(250));
             // TODO: You must take an action before you update a shared value
diff --git a/exercises/threads/threads3.rs b/exercises/threads/threads3.rs
index 9e9f285a..27e99088 100644
--- a/exercises/threads/threads3.rs
+++ b/exercises/threads/threads3.rs
@@ -26,8 +26,8 @@ impl Queue {
 
 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 qc1 = qc.clone();
+    let qc2 = qc.clone();
 
     thread::spawn(move || {
         for val in &qc1.first_half {
diff --git a/exercises/variables/variables1.rs b/exercises/variables/variables1.rs
index f4d182ac..84de9fdc 100644
--- a/exercises/variables/variables1.rs
+++ b/exercises/variables/variables1.rs
@@ -2,9 +2,7 @@
 // Make me compile!
 // 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/variables/variables2.rs b/exercises/variables/variables2.rs
index 641aeb8e..ea8b1076 100644
--- a/exercises/variables/variables2.rs
+++ b/exercises/variables/variables2.rs
@@ -1,10 +1,8 @@
 // variables2.rs
 // 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/variables/variables3.rs b/exercises/variables/variables3.rs
index 819b1bc7..619895fc 100644
--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -1,9 +1,7 @@
 // variables3.rs
 // 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 = 10;
     println!("Number {}", x);
 }
diff --git a/exercises/variables/variables4.rs b/exercises/variables/variables4.rs
index 54491b0a..8c2ddd6d 100644
--- a/exercises/variables/variables4.rs
+++ b/exercises/variables/variables4.rs
@@ -1,10 +1,8 @@
 // variables4.rs
 // 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/variables/variables5.rs b/exercises/variables/variables5.rs
index 0e670d2a..1b9d9f48 100644
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -1,11 +1,9 @@
 // variables5.rs
 // 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/variables/variables6.rs b/exercises/variables/variables6.rs
index a8520122..e8314b28 100644
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -1,9 +1,7 @@
 // variables6.rs
 // 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/vecs/vecs1.rs b/exercises/vecs/vecs1.rs
index 4e8c4cbb..f537f198 100644
--- a/exercises/vecs/vecs1.rs
+++ b/exercises/vecs/vecs1.rs
@@ -4,11 +4,9 @@
 // Make me compile and pass the test!
 // 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<i32> = vec![10, 20, 30, 40];
 
     (a, v)
 }
diff --git a/exercises/vecs/vecs2.rs b/exercises/vecs/vecs2.rs
index 5bea09a2..34bb23fd 100644
--- a/exercises/vecs/vecs2.rs
+++ b/exercises/vecs/vecs2.rs
@@ -6,13 +6,11 @@
 //
 // 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 i in v.iter_mut() {
         // TODO: Fill this up so that each element in the Vec `v` is
         // multiplied by 2.
-        ???
+        *i = *i * 2;
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
@@ -20,11 +18,13 @@ fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
 }
 
 fn vec_map(v: &Vec<i32>) -> Vec<i32> {
-    v.iter().map(|num| {
-        // TODO: Do the same thing as above - but instead of mutating the
-        // Vec, you can just return the new number!
-        ???
-    }).collect()
+    v.iter()
+        .map(|num| {
+            // TODO: Do the same thing as above - but instead of mutating the
+            // Vec, you can just return the new number!
+            return *num * 2;
+        })
+        .collect()
 }
 
 #[cfg(test)]