diff --git a/src/index.js b/src/index.js
index f16abeb..29ade6c 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,5 +1,13 @@
 const factorial = (number) => {
-    
+
+  if (number <= 0) return 1
+
+  let factorial = 1
+  for (let i = 1; i <= number; i++) {
+    factorial = factorial * i
   }
 
-  module.exports = factorial;
\ No newline at end of file
+  return factorial
+}
+
+module.exports = factorial;
\ No newline at end of file