diff --git a/exercises/02_basic_calculator/06_while/src/lib.rs b/exercises/02_basic_calculator/06_while/src/lib.rs
index dbc30eb..b39af2b 100644
--- a/exercises/02_basic_calculator/06_while/src/lib.rs
+++ b/exercises/02_basic_calculator/06_while/src/lib.rs
@@ -4,7 +4,13 @@ pub fn factorial(n: u32) -> u32 {
     // interprets as "I'll get back to this later", thus
     // suppressing type errors.
     // It panics at runtime.
-    todo!()
+    let mut result: u32 = 1; // base case
+    let mut i: u32 = 1;
+    while i <= n {
+        result *= i;
+        i += 1;
+    }
+    result
 }
 
 #[cfg(test)]