diff --git a/exercises/clippy/clippy1.rs b/exercises/clippy/clippy1.rs
index c5f84a9c..02a47f2a 100644
--- a/exercises/clippy/clippy1.rs
+++ b/exercises/clippy/clippy1.rs
@@ -6,12 +6,11 @@
 // check clippy's suggestions from the output to solve the exercise.
 // Execute `rustlings hint clippy1` for hints :)
 
-// 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/clippy/clippy2.rs b/exercises/clippy/clippy2.rs
index 37af9ed0..ec6af9e7 100644
--- a/exercises/clippy/clippy2.rs
+++ b/exercises/clippy/clippy2.rs
@@ -1,12 +1,11 @@
 // clippy2.rs
 // Make me compile! Execute `rustlings hint clippy2` for hints :)
 
-// 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/collections/hashmap1.rs b/exercises/collections/hashmap1.rs
index 64b5a7f3..bf3b53b8 100644
--- a/exercises/collections/hashmap1.rs
+++ b/exercises/collections/hashmap1.rs
@@ -11,15 +11,18 @@
 // Execute the command `rustlings hint hashmap1` if you need
 // hints.
 
-// 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("apple"), 1);
+    basket.insert(String::from("oranage"), 0);
+    basket.insert(String::from("a"), 1);
+    basket.insert(String::from("b"), 1);
 
     // TODO: Put more fruits in your basket here.
 
diff --git a/exercises/collections/hashmap2.rs b/exercises/collections/hashmap2.rs
index 0abe19ab..220ab1b5 100644
--- a/exercises/collections/hashmap2.rs
+++ b/exercises/collections/hashmap2.rs
@@ -12,9 +12,7 @@
 // Execute the command `rustlings hint hashmap2` if you need
 // hints.
 
-// I AM NOT DONE
-
-use std::collections::HashMap;
+ use std::collections::HashMap;
 
 #[derive(Hash, PartialEq, Eq)]
 enum Fruit {
@@ -38,6 +36,12 @@ 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 | Fruit::Mango | Fruit::Lychee => (),
+            _ => {
+                basket.insert(fruit, 1);
+            }
+        }
     }
 }
 
diff --git a/exercises/collections/vec1.rs b/exercises/collections/vec1.rs
index b144fb94..ddd39644 100644
--- a/exercises/collections/vec1.rs
+++ b/exercises/collections/vec1.rs
@@ -4,11 +4,10 @@
 // Make me compile and pass the test!
 // Execute the command `rustlings hint vec1` if you need hints.
 
-// 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/collections/vec2.rs b/exercises/collections/vec2.rs
index 6595e401..b5d37ec1 100644
--- a/exercises/collections/vec2.rs
+++ b/exercises/collections/vec2.rs
@@ -7,12 +7,12 @@
 // Execute the command `rustlings hint vec2` if you need
 // hints.
 
-// 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 *= 2;
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
diff --git a/exercises/conversions/from_into.rs b/exercises/conversions/from_into.rs
index 9d84174d..6121dfbd 100644
--- a/exercises/conversions/from_into.rs
+++ b/exercises/conversions/from_into.rs
@@ -37,6 +37,23 @@ impl Default for Person {
 
 impl From<&str> for Person {
     fn from(s: &str) -> Person {
+        let mut r = s.split(",");
+
+        let name = r.next();
+        let age = r.next();
+        let other = r.next();
+        if let (Some(name), Some(age), None) = (name, age, other) {
+            if name != "" && age != "" {
+                if let Ok(age) = age.parse() {
+                    return Person {
+                        name: name.to_string(),
+                        age,
+                    };
+                }
+            }
+        }
+
+        return Person::default();
     }
 }
 
diff --git a/exercises/conversions/using_as.rs b/exercises/conversions/using_as.rs
index f3f745ff..5ebf655d 100644
--- a/exercises/conversions/using_as.rs
+++ b/exercises/conversions/using_as.rs
@@ -5,11 +5,10 @@
 // The goal is to make sure that the division does not fail to compile
 // and returns the proper type.
 
-// 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/enums/enums1.rs b/exercises/enums/enums1.rs
index a2223d33..5f93b3c9 100644
--- a/exercises/enums/enums1.rs
+++ b/exercises/enums/enums1.rs
@@ -1,11 +1,12 @@
 // enums1.rs
 // Make me compile! Execute `rustlings hint enums1` for hints!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor, // TODO: define a few types of messages as used below
 }
 
 fn main() {
diff --git a/exercises/enums/enums2.rs b/exercises/enums/enums2.rs
index ec32d952..0168f14e 100644
--- a/exercises/enums/enums2.rs
+++ b/exercises/enums/enums2.rs
@@ -1,10 +1,13 @@
 // enums2.rs
 // Make me compile! Execute `rustlings hint enums2` for hints!
 
-// I AM NOT DONE
 
 #[derive(Debug)]
 enum Message {
+    Move{x:i32,y:i32},
+    Echo(String),
+    ChangeColor(i32,i32,i32),
+    Quit
     // TODO: define the different variants used below
 }
 
diff --git a/exercises/enums/enums3.rs b/exercises/enums/enums3.rs
index 178b40c4..e38f35fa 100644
--- a/exercises/enums/enums3.rs
+++ b/exercises/enums/enums3.rs
@@ -1,10 +1,11 @@
 // enums3.rs
 // Address all the TODOs to make the tests pass!
 
-// 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, // TODO: implement the message variant types based on their usage below
 }
 
 struct Point {
@@ -36,6 +37,14 @@ impl State {
     }
 
     fn process(&mut self, message: Message) {
+        match message {
+            Message::ChangeColor(color) => self.color = color,
+            Message::Echo(mes) => println!("{mes}"),
+            Message::Move(point) => {
+                self.position = point;
+            }
+            Message::Quit => self.quit = true,
+        }
         // TODO: create a match expression to process the different message variants
     }
 }
diff --git a/exercises/error_handling/errors1.rs b/exercises/error_handling/errors1.rs
index c417fb26..de9262a6 100644
--- a/exercises/error_handling/errors1.rs
+++ b/exercises/error_handling/errors1.rs
@@ -5,14 +5,12 @@
 // construct to `Option` that can be used to express error conditions. Let's use it!
 // Execute `rustlings hint errors1` for hints!
 
-// 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.len() > 0 {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     } else {
         // Empty names aren't allowed.
-        None
+        Err("`name` was empty; it must be nonempty.".to_string())
     }
 }
 
diff --git a/exercises/error_handling/errors2.rs b/exercises/error_handling/errors2.rs
index aad3a93f..cfc85373 100644
--- a/exercises/error_handling/errors2.rs
+++ b/exercises/error_handling/errors2.rs
@@ -16,14 +16,13 @@
 // There are at least two ways to implement this that are both correct-- but
 // one is a lot shorter! Execute `rustlings hint errors2` for hints to both ways.
 
-// I AM NOT DONE
 
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
+    let qty = item_quantity.parse::<i32>()?;
 
     Ok(qty * cost_per_item + processing_fee)
 }
diff --git a/exercises/error_handling/errors3.rs b/exercises/error_handling/errors3.rs
index 460ac5c4..b799ad8b 100644
--- a/exercises/error_handling/errors3.rs
+++ b/exercises/error_handling/errors3.rs
@@ -4,15 +4,13 @@
 // Why not? What should we do to fix it?
 // Execute `rustlings hint errors3` for hints!
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 fn main() {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
-    let cost = total_cost(pretend_user_input)?;
+    let cost = total_cost(pretend_user_input).unwrap();
 
     if cost > tokens {
         println!("You can't afford that many!");
diff --git a/exercises/error_handling/errors4.rs b/exercises/error_handling/errors4.rs
index 0685c374..a53f7a3f 100644
--- a/exercises/error_handling/errors4.rs
+++ b/exercises/error_handling/errors4.rs
@@ -1,8 +1,6 @@
 // errors4.rs
 // Make this test pass! Execute `rustlings hint errors4` for hints :)
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
 
@@ -14,7 +12,13 @@ enum CreationError {
 
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
-        Ok(PositiveNonzeroInteger(value as u64))
+        if value < 0{
+            Err(CreationError::Negative)
+        } else if value == 0 {
+            Err(CreationError::Zero)
+        } else {
+            Ok(PositiveNonzeroInteger(value as u64))
+        }
     }
 }
 
diff --git a/exercises/error_handling/errors5.rs b/exercises/error_handling/errors5.rs
index 365a8691..66889a33 100644
--- a/exercises/error_handling/errors5.rs
+++ b/exercises/error_handling/errors5.rs
@@ -4,14 +4,12 @@
 // It won't compile right now! Why?
 // Execute `rustlings hint errors5` for hints!
 
-// 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<(), ParseIntError> {
+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/error_handling/errors6.rs b/exercises/error_handling/errors6.rs
index 847a049a..b6470ab2 100644
--- a/exercises/error_handling/errors6.rs
+++ b/exercises/error_handling/errors6.rs
@@ -8,29 +8,30 @@
 
 // Make these tests pass! Execute `rustlings hint errors6` for hints :)
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 // This is a custom error type that we will be using in `parse_pos_nonzero()`.
 #[derive(PartialEq, Debug)]
 enum ParsePosNonzeroError {
     Creation(CreationError),
-    ParseInt(ParseIntError)
+    ParseInt(ParseIntError),
 }
 
 impl ParsePosNonzeroError {
     // TODO: add another error conversion function here.
+    fn from_creation(err: CreationError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::Creation(err)
+    }
+    fn from_parse_int(err: ParseIntError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::ParseInt(err)
+    }
 }
 
-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)
+    let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parse_int)?;
+    PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
 }
 
 // Don't change anything below this line.
@@ -49,7 +50,7 @@ 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 31125278..4f75b9a0 100644
--- a/exercises/functions/functions1.rs
+++ b/exercises/functions/functions1.rs
@@ -1,8 +1,9 @@
 // functions1.rs
 // Make me compile! Execute `rustlings hint functions1` for hints :)
 
-// I AM NOT DONE
 
 fn main() {
     call_me();
 }
+
+fn call_me() {}
diff --git a/exercises/functions/functions2.rs b/exercises/functions/functions2.rs
index 5721a172..fd72c3b4 100644
--- a/exercises/functions/functions2.rs
+++ b/exercises/functions/functions2.rs
@@ -1,13 +1,12 @@
 // functions2.rs
 // Make me compile! Execute `rustlings hint functions2` for hints :)
 
-// 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 ed5f839f..d1aea2f3 100644
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -1,10 +1,9 @@
 // functions3.rs
 // Make me compile! Execute `rustlings hint functions3` for hints :)
 
-// 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 58637e4c..0c3c6c30 100644
--- a/exercises/functions/functions4.rs
+++ b/exercises/functions/functions4.rs
@@ -4,14 +4,13 @@
 // This store is having a sale where if the price is an even number, you get
 // 10 Rustbucks off, but if it's an odd number, it's 3 Rustbucks off.
 
-// 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 d22aa6c8..ee79e792 100644
--- a/exercises/functions/functions5.rs
+++ b/exercises/functions/functions5.rs
@@ -1,7 +1,6 @@
 // functions5.rs
 // Make me compile! Execute `rustlings hint functions5` for hints :)
 
-// I AM NOT DONE
 
 fn main() {
     let answer = square(3);
@@ -9,5 +8,5 @@ fn main() {
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }
diff --git a/exercises/generics/generics1.rs b/exercises/generics/generics1.rs
index f93e64a0..228e0668 100644
--- a/exercises/generics/generics1.rs
+++ b/exercises/generics/generics1.rs
@@ -3,9 +3,8 @@
 
 // Execute `rustlings hint generics1` for hints!
 
-// 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/generics/generics2.rs b/exercises/generics/generics2.rs
index 1501529c..8c6a5100 100644
--- a/exercises/generics/generics2.rs
+++ b/exercises/generics/generics2.rs
@@ -3,14 +3,12 @@
 
 // Execute `rustlings hint generics2` for hints!
 
-// 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/generics/generics3.rs b/exercises/generics/generics3.rs
index 64dd9bc1..0bdd342a 100644
--- a/exercises/generics/generics3.rs
+++ b/exercises/generics/generics3.rs
@@ -10,18 +10,18 @@
 
 // Execute 'rustlings hint generics3' for hints!
 
-// I AM NOT DONE
-
-pub struct ReportCard {
-    pub grade: f32,
+pub struct ReportCard<T: std::fmt::Display> {
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T: std::fmt::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
+        )
     }
 }
 
@@ -46,7 +46,7 @@ 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+",
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };
diff --git a/exercises/if/if1.rs b/exercises/if/if1.rs
index 90867545..b0ff48d1 100644
--- a/exercises/if/if1.rs
+++ b/exercises/if/if1.rs
@@ -1,6 +1,5 @@
 // if1.rs
 
-// I AM NOT DONE
 
 pub fn bigger(a: i32, b: i32) -> i32 {
     // Complete this function to return the bigger number!
@@ -8,6 +7,8 @@ pub fn bigger(a: i32, b: i32) -> i32 {
     // - another function call
     // - additional variables
     // Execute `rustlings hint if1` for hints
+    
+    if a > b {a} else {b}
 }
 
 // Don't mind this for now :)
diff --git a/exercises/if/if2.rs b/exercises/if/if2.rs
index 80effbdf..4d1ab2d4 100644
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -4,13 +4,14 @@
 // Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
 // Execute the command `rustlings hint if2` if you want a hint :)
 
-// I AM NOT DONE
 
 pub fn fizz_if_foo(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 1c4582de..3b11d4a2 100644
--- a/exercises/intro/intro1.rs
+++ b/exercises/intro/intro1.rs
@@ -5,8 +5,6 @@
 // ready for the next exercise, remove the `I AM NOT DONE` comment below.
 // Execute the command `rustlings hint intro1` for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     println!("Hello and");
     println!(r#"       welcome to...                      "#);
diff --git a/exercises/intro/intro2.rs b/exercises/intro/intro2.rs
index 97a073f0..4a51c1bc 100644
--- a/exercises/intro/intro2.rs
+++ b/exercises/intro/intro2.rs
@@ -2,8 +2,6 @@
 // Make the code print a greeting to the world.
 // Execute `rustlings hint intro2` for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    println!("Hello {}!");
+    println!("a greeting to the world.");
 }
diff --git a/exercises/macros/macros1.rs b/exercises/macros/macros1.rs
index ed0dac85..6f812d02 100644
--- a/exercises/macros/macros1.rs
+++ b/exercises/macros/macros1.rs
@@ -1,7 +1,6 @@
 // macros1.rs
 // Make me compile! Execute `rustlings hint macros1` for hints :)
 
-// I AM NOT DONE
 
 macro_rules! my_macro {
     () => {
@@ -10,5 +9,5 @@ macro_rules! my_macro {
 }
 
 fn main() {
-    my_macro();
+    my_macro!();
 }
diff --git a/exercises/macros/macros2.rs b/exercises/macros/macros2.rs
index d0be1236..7fe36eb6 100644
--- a/exercises/macros/macros2.rs
+++ b/exercises/macros/macros2.rs
@@ -1,14 +1,15 @@
 // macros2.rs
 // Make me compile! Execute `rustlings hint macros2` for hints :)
 
-// 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/macros/macros3.rs b/exercises/macros/macros3.rs
index 93a43113..dda45f39 100644
--- a/exercises/macros/macros3.rs
+++ b/exercises/macros/macros3.rs
@@ -2,10 +2,10 @@
 // Make me compile, without taking the macro out of the module!
 // Execute `rustlings hint macros3` for hints :)
 
-// I AM NOT DONE
 
 mod macros {
-    macro_rules! my_macro {
+    #[macro_export]
+     macro_rules! my_macro {
         () => {
             println!("Check out my macro!");
         };
diff --git a/exercises/macros/macros4.rs b/exercises/macros/macros4.rs
index 3a748078..5608ecc6 100644
--- a/exercises/macros/macros4.rs
+++ b/exercises/macros/macros4.rs
@@ -1,15 +1,13 @@
 // macros4.rs
 // Make me compile! Execute `rustlings hint macros4` for hints :)
 
-// I AM NOT DONE
-
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
-    }
+    };
     ($val:expr) => {
         println!("Look at this other macro: {}", $val);
-    }
+    };
 }
 
 fn main() {
diff --git a/exercises/modules/modules1.rs b/exercises/modules/modules1.rs
index 1a2bd0dd..2bfff9bb 100644
--- a/exercises/modules/modules1.rs
+++ b/exercises/modules/modules1.rs
@@ -1,7 +1,6 @@
 // modules1.rs
 // Make me compile! Execute `rustlings hint modules1` for hints :)
 
-// I AM NOT DONE
 
 mod sausage_factory {
     // Don't let anybody outside of this module see this!
@@ -9,7 +8,7 @@ mod sausage_factory {
         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 87f0c458..6c859f2c 100644
--- a/exercises/modules/modules2.rs
+++ b/exercises/modules/modules2.rs
@@ -3,13 +3,12 @@
 // 'use' and 'as' keywords. Fix these 'use' statements to make the code compile.
 // Make me compile! Execute `rustlings hint modules2` for hints :)
 
-// 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 const PEAR: &'static str = "Pear";
diff --git a/exercises/modules/modules3.rs b/exercises/modules/modules3.rs
index 8eed77df..1cb89dd9 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!
 // Make me compile! Execute `rustlings hint modules3` for hints :)
 
-// 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/move_semantics/move_semantics1.rs b/exercises/move_semantics/move_semantics1.rs
index e2f5876d..78e4f8aa 100644
--- a/exercises/move_semantics/move_semantics1.rs
+++ b/exercises/move_semantics/move_semantics1.rs
@@ -1,12 +1,11 @@
 // move_semantics1.rs
 // Make me compile! Execute `rustlings hint move_semantics1` for hints :)
 
-// 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 888dc529..7a594b0d 100644
--- a/exercises/move_semantics/move_semantics2.rs
+++ b/exercises/move_semantics/move_semantics2.rs
@@ -2,12 +2,11 @@
 // Make me compile without changing line 13 or moving line 10!
 // Execute `rustlings hint move_semantics2` for hints :)
 
-// I AM NOT DONE
 
 fn main() {
     let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(&vec0);
 
     // Do not change the following line!
     println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
@@ -17,8 +16,8 @@ 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:& Vec<i32>) -> Vec<i32> {
+    let mut vec = vec.clone();
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/move_semantics/move_semantics3.rs b/exercises/move_semantics/move_semantics3.rs
index 43fef74f..6556c2fe 100644
--- a/exercises/move_semantics/move_semantics3.rs
+++ b/exercises/move_semantics/move_semantics3.rs
@@ -3,12 +3,11 @@
 // (no lines with multiple semicolons necessary!)
 // Execute `rustlings hint move_semantics3` for hints :)
 
-// 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);
 
@@ -17,7 +16,7 @@ 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>) ->&mut Vec<i32> {
     vec.push(22);
     vec.push(44);
     vec.push(66);
diff --git a/exercises/move_semantics/move_semantics4.rs b/exercises/move_semantics/move_semantics4.rs
index 2a23c710..c3cf03d3 100644
--- a/exercises/move_semantics/move_semantics4.rs
+++ b/exercises/move_semantics/move_semantics4.rs
@@ -4,12 +4,8 @@
 // freshly created vector from fill_vec to its caller.
 // Execute `rustlings hint move_semantics4` for hints!
 
-// 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 c4704f9e..409e5337 100644
--- a/exercises/move_semantics/move_semantics5.rs
+++ b/exercises/move_semantics/move_semantics5.rs
@@ -3,13 +3,12 @@
 // adding, changing or removing any of them.
 // Execute `rustlings hint move_semantics5` for hints :)
 
-// 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 457e7ae7..f09df2ba 100644
--- a/exercises/move_semantics/move_semantics6.rs
+++ b/exercises/move_semantics/move_semantics6.rs
@@ -2,24 +2,22 @@
 // Make me compile! `rustlings hint move_semantics6` for hints
 // 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/option/option1.rs b/exercises/option/option1.rs
index 17cf4f60..911ed867 100644
--- a/exercises/option/option1.rs
+++ b/exercises/option/option1.rs
@@ -1,23 +1,19 @@
 // option1.rs
 // Make me compile! Execute `rustlings hint option1` for hints
 
-// I AM NOT DONE
-
 // you can modify anything EXCEPT for this function's signature
 fn print_number(maybe_number: Option<u16>) {
     println!("printing: {}", maybe_number.unwrap());
 }
 
 fn main() {
-    print_number(13);
-    print_number(99);
+    print_number(Some(13));
+    print_number(Some(99));
 
-    let mut numbers: [Option<u16>; 5];
+    let mut numbers: [Option<u16>; 5] = [None;5];
     for iter in 0..5 {
-        let number_to_add: u16 = {
-            ((iter * 1235) + 2) / (4 * 16)
-        };
+        let number_to_add: u16 = { ((iter * 1235) + 2) / (4 * 16) };
 
-        numbers[iter as usize] = number_to_add;
+        numbers[iter as usize] = Some(number_to_add);
     }
 }
diff --git a/exercises/option/option2.rs b/exercises/option/option2.rs
index c6b83ece..f6c786f5 100644
--- a/exercises/option/option2.rs
+++ b/exercises/option/option2.rs
@@ -1,12 +1,11 @@
 // option2.rs
 // Make me compile! Execute `rustlings hint option2` for hints
 
-// I AM NOT DONE
 
 fn main() {
     let optional_word = Some(String::from("rustlings"));
     // TODO: Make this an if let statement whose value is "Some" type
-    word = optional_word {
+    if let Some(word) = optional_word {
         println!("The word is: {}", word);
     } else {
         println!("The optional word doesn't contain anything");
@@ -19,7 +18,7 @@ fn main() {
 
     // 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_vec.pop() {
+    if let Some(Some(integer)) = optional_integers_vec.pop() {
         println!("current value: {}", integer);
     }
 }
diff --git a/exercises/option/option3.rs b/exercises/option/option3.rs
index 045d2acb..e35445da 100644
--- a/exercises/option/option3.rs
+++ b/exercises/option/option3.rs
@@ -1,7 +1,6 @@
 // option3.rs
 // Make me compile! Execute `rustlings hint option3` for hints
 
-// I AM NOT DONE
 
 struct Point {
     x: i32,
@@ -12,7 +11,7 @@ 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),
         _ => println!("no match"),
     }
     y; // Fix without deleting this line.
diff --git a/exercises/primitive_types/primitive_types1.rs b/exercises/primitive_types/primitive_types1.rs
index 09121392..53330d37 100644
--- a/exercises/primitive_types/primitive_types1.rs
+++ b/exercises/primitive_types/primitive_types1.rs
@@ -2,7 +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 +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; // 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 6576a4d5..d6ba451e 100644
--- a/exercises/primitive_types/primitive_types2.rs
+++ b/exercises/primitive_types/primitive_types2.rs
@@ -2,7 +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`)
@@ -16,7 +15,7 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
+    let your_character = 'f'; // 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() {
diff --git a/exercises/primitive_types/primitive_types3.rs b/exercises/primitive_types/primitive_types3.rs
index aaa518be..134b1415 100644
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -2,10 +2,9 @@
 // Create an array with at least 100 elements in it where the ??? is.
 // Execute `rustlings hint primitive_types3` for hints!
 
-// 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 10b553e9..df54dff0 100644
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -2,13 +2,12 @@
 // Get a slice out of Array a where the ??? is so that the test passes.
 // Execute `rustlings hint primitive_types4` for hints!!
 
-// 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 680d8d23..5faa23c1 100644
--- a/exercises/primitive_types/primitive_types5.rs
+++ b/exercises/primitive_types/primitive_types5.rs
@@ -2,11 +2,10 @@
 // Destructure the `cat` tuple so that the println will work.
 // Execute `rustlings hint primitive_types5` for hints!
 
-// I AM NOT DONE
 
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name,age)/* your pattern here */ = cat;
 
     println!("{} is {} years old.", name, age);
 }
diff --git a/exercises/primitive_types/primitive_types6.rs b/exercises/primitive_types/primitive_types6.rs
index b8c9b82b..86b52692 100644
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -3,13 +3,12 @@
 // You can put the expression for the second element where ??? is so that the test passes.
 // Execute `rustlings hint primitive_types6` for hints!
 
-// 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/quiz1.rs b/exercises/quiz1.rs
index 7bd3f589..2b077970 100644
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -8,7 +8,6 @@
 // more than 40 at once, each apple only costs 1! 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_apple_price {
@@ -24,3 +23,11 @@ fn verify_test() {
     assert_eq!(80, price2);
     assert_eq!(65, price3);
 }
+
+fn calculate_apple_price(apple: i32)->i32{
+    if apple <= 40 {
+        apple * 2
+    } else {
+        apple * 1
+    }
+}
\ No newline at end of file
diff --git a/exercises/quiz2.rs b/exercises/quiz2.rs
index de0dce95..8beed12b 100644
--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -7,7 +7,6 @@
 // you think each value is. That is, add either `string_slice` or `string`
 // before the parentheses on each line. If you're right, it will compile!
 
-// I AM NOT DONE
 
 fn string_slice(arg: &str) {
     println!("{}", arg);
@@ -17,14 +16,14 @@ 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/quiz3.rs b/exercises/quiz3.rs
index fae0eedb..d76bd95e 100644
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -7,7 +7,6 @@
 // we expect to get when we call `times_two` with a negative number.
 // No hints, you can do this :)
 
-// I AM NOT DONE
 
 pub fn times_two(num: i32) -> i32 {
     num * 2
@@ -19,12 +18,13 @@ mod tests {
 
     #[test]
     fn returns_twice_of_positive_numbers() {
-        assert_eq!(times_two(4), ???);
+        assert_eq!(times_two(4),8) 
     }
 
     #[test]
     fn returns_twice_of_negative_numbers() {
         // TODO replace unimplemented!() with an assert for `times_two(-4)`
-        unimplemented!()
+        // unimplemented!()
+        assert_eq!(times_two(-4),-8)
     }
 }
diff --git a/exercises/quiz4.rs b/exercises/quiz4.rs
index 6c47480d..a2081eef 100644
--- a/exercises/quiz4.rs
+++ b/exercises/quiz4.rs
@@ -5,7 +5,19 @@
 
 // Write a macro that passes the quiz! No hints this time, you can do it!
 
-// I AM NOT DONE
+mod m {
+    #[macro_export]
+    macro_rules! my_macro {
+        ($val:expr) => {
+            {
+                let mut s = String::from("Hello ");
+                s.push_str($val);
+                s
+            }
+        //    format!("Hello {}",$val)
+        };
+    }
+}
 
 #[cfg(test)]
 mod tests {
@@ -13,6 +25,7 @@ mod tests {
 
     #[test]
     fn test_my_macro_world() {
+        my_macro!("world!");
         assert_eq!(my_macro!("world!"), "Hello world!");
     }
 
diff --git a/exercises/standard_library_types/arc1.rs b/exercises/standard_library_types/arc1.rs
index f60061e7..1d139a25 100644
--- a/exercises/standard_library_types/arc1.rs
+++ b/exercises/standard_library_types/arc1.rs
@@ -18,19 +18,17 @@
 // where the second TODO comment is. Try not to create any copies of the `numbers` Vec!
 // Execute `rustlings hint arc1` for hints :)
 
-// 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); // TODO
     let mut joinhandles = Vec::new();
 
     for offset in 0..8 {
-        let child_numbers = // TODO
+        let child_numbers = Arc::clone(&shared_numbers); // TODO
         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/standard_library_types/box1.rs b/exercises/standard_library_types/box1.rs
index f312f3d6..cf3492a6 100644
--- a/exercises/standard_library_types/box1.rs
+++ b/exercises/standard_library_types/box1.rs
@@ -16,11 +16,10 @@
 //
 // Execute `rustlings hint box1` for hints :)
 
-// I AM NOT DONE
 
 #[derive(PartialEq, Debug)]
 pub enum List {
-    Cons(i32, List),
+    Cons(i32, Box<List>),
     Nil,
 }
 
@@ -33,11 +32,13 @@ fn main() {
 }
 
 pub fn create_empty_list() -> List {
-    unimplemented!()
+    // unimplemented!()
+    List::Nil
 }
 
 pub fn create_non_empty_list() -> List {
-    unimplemented!()
+    // unimplemented!()
+    List::Cons(1,Box::new(List::Nil))
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators1.rs b/exercises/standard_library_types/iterators1.rs
index 5aa49b64..57236724 100644
--- a/exercises/standard_library_types/iterators1.rs
+++ b/exercises/standard_library_types/iterators1.rs
@@ -8,17 +8,16 @@
 //
 // Execute `rustlings hint iterators1` for hints :D
 
-// I AM NOT DONE
 
 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/standard_library_types/iterators2.rs b/exercises/standard_library_types/iterators2.rs
index 87b4eaa1..4619f56f 100644
--- a/exercises/standard_library_types/iterators2.rs
+++ b/exercises/standard_library_types/iterators2.rs
@@ -3,7 +3,6 @@
 // can offer. Follow the steps to complete the exercise.
 // As always, there are hints if you execute `rustlings hint iterators2`!
 
-// I AM NOT DONE
 
 // Step 1.
 // Complete the `capitalize_first` function.
@@ -12,7 +11,7 @@ pub fn capitalize_first(input: &str) -> String {
     let mut c = input.chars();
     match c.next() {
         None => String::new(),
-        Some(first) => ???,
+        Some(first) => input.replace(first, &first.to_uppercase().to_string()),
     }
 }
 
@@ -21,7 +20,11 @@ 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![]
+    let mut result = vec![];
+    for word in words {
+        result.push(capitalize_first(word));
+    }
+    result
 }
 
 // Step 3.
@@ -29,7 +32,7 @@ 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()
+    capitalize_words_vector(words).join("")
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators3.rs b/exercises/standard_library_types/iterators3.rs
index 8c66c05b..433ca8cf 100644
--- a/exercises/standard_library_types/iterators3.rs
+++ b/exercises/standard_library_types/iterators3.rs
@@ -6,8 +6,6 @@
 //    list_of_results functions.
 // Execute `rustlings hint iterators3` to get some hints!
 
-// I AM NOT DONE
-
 #[derive(Debug, PartialEq, Eq)]
 pub enum DivisionError {
     NotDivisible(NotDivisibleError),
@@ -22,20 +20,36 @@ 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> {}
+pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
+    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::<Result<Vec<i32>, DivisionError>>();
+    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/standard_library_types/iterators4.rs b/exercises/standard_library_types/iterators4.rs
index 88862838..dc2fd37c 100644
--- a/exercises/standard_library_types/iterators4.rs
+++ b/exercises/standard_library_types/iterators4.rs
@@ -1,7 +1,5 @@
 // iterators4.rs
 
-// I AM NOT DONE
-
 pub fn factorial(num: u64) -> u64 {
     // Complete this function to return the factorial of num
     // Do not use:
@@ -12,6 +10,13 @@ pub fn factorial(num: u64) -> u64 {
     // For an extra challenge, don't use:
     // - recursion
     // Execute `rustlings hint iterators4` for hints.
+    // if num == 1  {
+    //     1
+    // }else {
+    //     num * factorial(num - 1)
+    // }
+
+    (1..=num).fold(1, |acc, x| acc * x)
 }
 
 #[cfg(test)]
@@ -29,6 +34,7 @@ mod tests {
 
     #[test]
     fn factorial_of_4() {
+        // 1 * 2 * 3 * 4
         assert_eq!(24, factorial(4));
     }
 }
diff --git a/exercises/standard_library_types/iterators5.rs b/exercises/standard_library_types/iterators5.rs
index 93f3ae11..c20283b8 100644
--- a/exercises/standard_library_types/iterators5.rs
+++ b/exercises/standard_library_types/iterators5.rs
@@ -10,7 +10,6 @@
 //
 // Make the code compile and the tests pass.
 
-// I AM NOT DONE
 
 use std::collections::HashMap;
 
@@ -34,6 +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, ... }
+    map.values().filter(|v|{if v == &&value {true} else {false}}).count()
 }
 
 fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
@@ -52,6 +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, ... }, ... ]
+    collection.iter().map(|hash|count_iterator(hash,value)).sum()
 }
 
 #[cfg(test)]
diff --git a/exercises/strings/strings1.rs b/exercises/strings/strings1.rs
index 80902444..aff1a4ac 100644
--- a/exercises/strings/strings1.rs
+++ b/exercises/strings/strings1.rs
@@ -2,7 +2,6 @@
 // Make me compile without changing the function signature!
 // Execute `rustlings hint strings1` for hints ;)
 
-// I AM NOT DONE
 
 fn main() {
     let answer = current_favorite_color();
@@ -10,5 +9,5 @@ fn main() {
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    "blue".to_string()
 }
diff --git a/exercises/strings/strings2.rs b/exercises/strings/strings2.rs
index 5a2ce74a..a048f882 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` for hints :)
 
-// 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/structs/structs1.rs b/exercises/structs/structs1.rs
index 6d0b2f49..160c1a56 100644
--- a/exercises/structs/structs1.rs
+++ b/exercises/structs/structs1.rs
@@ -1,13 +1,13 @@
 // structs1.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
-struct ColorClassicStruct {
+struct ColorClassicStruct<'a> {
     // TODO: Something goes here
+    name: &'a str,
+    hex: &'a str,
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+struct ColorTupleStruct<'a>(/* TODO: Something goes here */&'a str,&'a str);
 
 #[derive(Debug)]
 struct UnitStruct;
@@ -19,7 +19,7 @@ mod tests {
     #[test]
     fn classic_c_structs() {
         // TODO: Instantiate a classic c struct!
-        // let green =
+        let green = ColorClassicStruct {name:"green",hex:"#00FF00"};
 
         assert_eq!(green.name, "green");
         assert_eq!(green.hex, "#00FF00");
@@ -28,7 +28,7 @@ mod tests {
     #[test]
     fn tuple_structs() {
         // TODO: Instantiate a tuple struct!
-        // let green =
+        let green = ("green","#00FF00");
 
         assert_eq!(green.0, "green");
         assert_eq!(green.1, "#00FF00");
@@ -37,7 +37,7 @@ mod tests {
     #[test]
     fn unit_structs() {
         // TODO: Instantiate a unit struct!
-        // let unit_struct =
+        let unit_struct = UnitStruct;
         let message = format!("{:?}s are fun!", unit_struct);
 
         assert_eq!(message, "UnitStructs are fun!");
diff --git a/exercises/structs/structs2.rs b/exercises/structs/structs2.rs
index f9c6427d..d9f55ed6 100644
--- a/exercises/structs/structs2.rs
+++ b/exercises/structs/structs2.rs
@@ -1,8 +1,6 @@
 // structs2.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Order {
     name: String,
@@ -34,7 +32,15 @@ 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"),
+            year: 2019,
+            made_by_email: true,
+            made_by_mobile: false,
+            made_by_phone: false,
+            item_number: 123,
+            count: 1,
+        };
         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 e84f2ebc..aedaf7e9 100644
--- a/exercises/structs/structs3.rs
+++ b/exercises/structs/structs3.rs
@@ -4,7 +4,6 @@
 // Make the code compile and the tests pass!
 // If you have issues execute `rustlings hint structs3`
 
-// I AM NOT DONE
 
 #[derive(Debug)]
 struct Package {
@@ -17,6 +16,7 @@ impl Package {
     fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
         if weight_in_grams <= 0 {
             // panic statement goes here...
+            panic!("error");
         } else {
             Package {
                 sender_country,
@@ -26,12 +26,14 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
+    fn is_international(&self) -> bool {
         // Something goes here...
+        self.sender_country == "Spain" && self.sender_country != "Canada"
     }
 
-    fn get_fees(&self, cents_per_gram: i32) -> ??? {
+    fn get_fees(&self, cents_per_gram: i32) -> i32 {
         // Something goes here...
+        self.weight_in_grams * cents_per_gram
     }
 }
 
diff --git a/exercises/tests/tests1.rs b/exercises/tests/tests1.rs
index 50586a19..955f4232 100644
--- a/exercises/tests/tests1.rs
+++ b/exercises/tests/tests1.rs
@@ -6,12 +6,11 @@
 // This test has a problem with it -- make the test compile! Make the test
 // pass! Make the test fail! Execute `rustlings hint tests1` for hints :)
 
-// I AM NOT DONE
 
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert() {
-        assert!();
+        assert!(true);
     }
 }
diff --git a/exercises/tests/tests2.rs b/exercises/tests/tests2.rs
index 0d981ad1..b3cc15fa 100644
--- a/exercises/tests/tests2.rs
+++ b/exercises/tests/tests2.rs
@@ -2,12 +2,11 @@
 // This test has a problem with it -- make the test compile! Make the test
 // pass! Make the test fail! Execute `rustlings hint tests2` for hints :)
 
-// I AM NOT DONE
 
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert_eq() {
-        assert_eq!();
+        assert_eq!(1, 1);
     }
 }
diff --git a/exercises/tests/tests3.rs b/exercises/tests/tests3.rs
index 3424f940..8cabd054 100644
--- a/exercises/tests/tests3.rs
+++ b/exercises/tests/tests3.rs
@@ -4,7 +4,6 @@
 // we expect to get when we call `is_even(5)`.
 // Execute `rustlings hint tests3` for hints :)
 
-// I AM NOT DONE
 
 pub fn is_even(num: i32) -> bool {
     num % 2 == 0
@@ -16,11 +15,11 @@ 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/threads/threads1.rs b/exercises/threads/threads1.rs
index f31b317e..5641c43e 100644
--- a/exercises/threads/threads1.rs
+++ b/exercises/threads/threads1.rs
@@ -6,9 +6,8 @@
 // of "waiting..." and the program ends without timing out when running,
 // you've got it :)
 
-// I AM NOT DONE
 
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
 
@@ -17,15 +16,16 @@ struct JobStatus {
 }
 
 fn main() {
-    let status = Arc::new(JobStatus { jobs_completed: 0 });
+    let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));
     let status_shared = status.clone();
     thread::spawn(move || {
         for _ in 0..10 {
             thread::sleep(Duration::from_millis(250));
-            status_shared.jobs_completed += 1;
+            let mut job = status_shared.lock().unwrap();
+            job.jobs_completed += 1;
         }
     });
-    while status.jobs_completed < 10 {
+    while status.lock().unwrap().jobs_completed < 10 {
         println!("waiting... ");
         thread::sleep(Duration::from_millis(500));
     }
diff --git a/exercises/traits/traits1.rs b/exercises/traits/traits1.rs
index 15e08f24..398f46f9 100644
--- a/exercises/traits/traits1.rs
+++ b/exercises/traits/traits1.rs
@@ -8,7 +8,6 @@
 // which appends "Bar" to any object
 // implementing this trait.
 
-// I AM NOT DONE
 
 trait AppendBar {
     fn append_bar(self) -> Self;
@@ -16,6 +15,12 @@ trait AppendBar {
 
 impl AppendBar for String {
     //Add your code here
+    fn append_bar(self)->Self{
+        // let mut s = self.clone();
+        // s.push_str("Bar");
+        // s
+        format!("{}{}",self,"Bar")
+    }
 }
 
 fn main() {
diff --git a/exercises/traits/traits2.rs b/exercises/traits/traits2.rs
index 916c3c4b..97a44867 100644
--- a/exercises/traits/traits2.rs
+++ b/exercises/traits/traits2.rs
@@ -10,13 +10,17 @@
 // No boiler plate code this time,
 // you can do this!
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
 //TODO: Add your code here
+impl AppendBar for Vec<String>{
+    fn append_bar(mut self) -> Self{
+        self.push("Bar".to_string());
+        self
+    }
+}
 
 #[cfg(test)]
 mod tests {
diff --git a/exercises/variables/variables1.rs b/exercises/variables/variables1.rs
index d1af8311..f41da792 100644
--- a/exercises/variables/variables1.rs
+++ b/exercises/variables/variables1.rs
@@ -2,9 +2,7 @@
 // Make me compile!
 // Execute the command `rustlings hint variables1` if you want 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 7774a8fb..be2ca14e 100644
--- a/exercises/variables/variables2.rs
+++ b/exercises/variables/variables2.rs
@@ -1,10 +1,9 @@
 // variables2.rs
 // Make me compile! Execute the command `rustlings hint variables2` if you want a hint :)
 
-// I AM NOT DONE
 
 fn main() {
-    let x;
+    let x = 10;
     if x == 10 {
         println!("Ten!");
     } else {
diff --git a/exercises/variables/variables3.rs b/exercises/variables/variables3.rs
index 30ec48ff..3566ef22 100644
--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -1,10 +1,9 @@
 // variables3.rs
 // Make me compile! Execute the command `rustlings hint variables3` if you want 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/variables4.rs b/exercises/variables/variables4.rs
index 77f1e9ab..e9285cfc 100644
--- a/exercises/variables/variables4.rs
+++ b/exercises/variables/variables4.rs
@@ -1,9 +1,8 @@
 // variables4.rs
 // Make me compile! Execute the command `rustlings hint variables4` if you want a hint :)
 
-// I AM NOT DONE
 
 fn main() {
-    let x: i32;
+    let x: i32 = 1;
     println!("Number {}", x);
 }
diff --git a/exercises/variables/variables5.rs b/exercises/variables/variables5.rs
index 175eebb3..d61e6c1b 100644
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -1,11 +1,10 @@
 // variables5.rs
 // Make me compile! Execute the command `rustlings hint variables5` if you want 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;
+    let number = 3;
     println!("Number plus two is : {}", number + 2);
 }
diff --git a/exercises/variables/variables6.rs b/exercises/variables/variables6.rs
index 98666914..4cd02e60 100644
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -1,9 +1,8 @@
 // variables6.rs
 // Make me compile! Execute the command `rustlings hint variables6` if you want a hint :)
 
-// I AM NOT DONE
 
-const NUMBER = 3;
+const NUMBER:i32 = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }