diff --git a/index.py b/index.py
new file mode 100644
index 0000000..6ea60c4
--- /dev/null
+++ b/index.py
@@ -0,0 +1,12 @@
+def factorial_iterative(n):
+    if not isinstance(n, int) or n < 0:
+        raise ValueError("Input must be a non-negative integer")
+    
+    result = 1
+    for i in range(1, n + 1):
+        result *= i
+    return result
+
+# SIX SEVEN
+number = 67
+print(f"The factorial of {number} is {factorial_iterative(number)}")