complete 02/[0,1,2]

exercises/02_basic_calculator/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to build a calculator in Rust!"
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/01_integers/src/lib.rs

@@ -1,7 +1,7 @@
 fn compute(a: u32, b: u32) -> u32 {
     // TODO: change the line below to fix the compiler error and make the tests pass.
     let multiplier: u8 = 4;
-    a + b * multiplier
+    a + b * multiplier as u32
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/02_variables/src/lib.rs

@@ -8,7 +8,7 @@
 pub fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
     // TODO: define a variable named `distance` with the right value to get tests to pass
     //  Do you need to annotate the type of `distance`? Why or why not?
-
+    let distance = end - start;
     // Don't change the line below
     distance / time_elapsed
 }