diff --git a/001/solution.rs b/001/solution.rs
index 48100c0..0d65fb7 100644
--- a/001/solution.rs
+++ b/001/solution.rs
@@ -1,5 +1,18 @@
+// https://projecteuler.net/problem=1 
 
 fn main() {
-        println!("hello world");
+        let mut sum = 0;
+        for n in 1..= 999 {
+                if n % 3 == 0 {
+                        sum += n;
+                        // println!("-- # {}", n);
+                }
+
+                if n % 5 == 0 && n % 3 != 0 {
+                        // println!("++ # {}", n);
+                        sum += n;
+                }
+        }
+        println!("{}", sum);
 }