diff --git a/exercises/02_functions/functions1.rs b/exercises/02_functions/functions1.rs
index 40ed9a07..a5401dea 100644
--- a/exercises/02_functions/functions1.rs
+++ b/exercises/02_functions/functions1.rs
@@ -3,8 +3,9 @@
 // Execute `rustlings hint functions1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
-    call_me();
+    fn call_me() {
+
+    };
 }
diff --git a/exercises/02_functions/functions2.rs b/exercises/02_functions/functions2.rs
index 5154f34d..318f80d0 100644
--- a/exercises/02_functions/functions2.rs
+++ b/exercises/02_functions/functions2.rs
@@ -3,13 +3,12 @@
 // Execute `rustlings hint functions2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
     call_me(3);
 }
 
-fn call_me(num:) {
+fn call_me(num:i32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }
diff --git a/exercises/02_functions/functions3.rs b/exercises/02_functions/functions3.rs
index 74f44d6d..cbd1fa6b 100644
--- a/exercises/02_functions/functions3.rs
+++ b/exercises/02_functions/functions3.rs
@@ -3,10 +3,9 @@
 // Execute `rustlings hint functions3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
-    call_me();
+    call_me(10000);
 }
 
 fn call_me(num: u32) {
diff --git a/exercises/02_functions/functions4.rs b/exercises/02_functions/functions4.rs
index 77c4b2aa..9fce4d44 100644
--- a/exercises/02_functions/functions4.rs
+++ b/exercises/02_functions/functions4.rs
@@ -8,14 +8,13 @@
 // Execute `rustlings hint functions4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
-    let original_price = 51;
+    let original_price: u32 = 51;
     println!("Your sale price is {}", sale_price(original_price));
 }
 
-fn sale_price(price: i32) -> {
+fn sale_price(price: u32) -> u32 {
     if is_even(price) {
         price - 10
     } else {
@@ -23,6 +22,6 @@ fn sale_price(price: i32) -> {
     }
 }
 
-fn is_even(num: i32) -> bool {
+fn is_even(num: u32) -> bool {
     num % 2 == 0
 }
diff --git a/exercises/02_functions/functions5.rs b/exercises/02_functions/functions5.rs
index f1b63f48..c49123ce 100644
--- a/exercises/02_functions/functions5.rs
+++ b/exercises/02_functions/functions5.rs
@@ -3,7 +3,6 @@
 // Execute `rustlings hint functions5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
     let answer = square(3);
@@ -11,5 +10,5 @@ fn main() {
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    return num * num;
 }