diff --git a/index.js b/index.js
index 2d7e6834fb6366b3120c7a37cc5f637bc4a33928..1c4e396c97810efa67cc9cd2ae9e618557b5ca80 100644
--- a/index.js
+++ b/index.js
@@ -1 +1,9 @@
-console.log("欢迎来到 InsCode");
\ No newline at end of file
+function factorial(n) {
+  if (n === 0) {
+    return 1;
+  } else {
+    return n * factorial(n - 1);
+  }
+}
+
+console.log(factorial(5)); // 输出 120
\ No newline at end of file