diff --git a/src/index.js b/src/index.js
index f16abeb..5763831 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,5 +1,14 @@
 const factorial = (number) => {
-    
+  
+    if(number === 0) {
+      return 1;
+    } else {
+      for(let i = number-1; i > 0; i--) {
+        number *= i;
+      }
+      return number;
+    }
+
   }
 
   module.exports = factorial;
\ No newline at end of file