diff --git a/simple_functions/functions1.py b/simple_functions/functions1.py
index 8c63a4d..070774b 100644
--- a/simple_functions/functions1.py
+++ b/simple_functions/functions1.py
@@ -1,9 +1,13 @@
+from functools import cache
+__all__ = ['my_sum', 'factorial']
 
-__all__ = ['my_sum']
-
-
+# ?????
 def my_sum(iterable):
     tot = 0
     for i in iterable:
         tot += i
     return tot
+
+@cache 
+def factorial(n):
+    return n * factorial(n-1) if n else 1
\ No newline at end of file
diff --git a/tests/test_simple_functions.py b/tests/test_simple_functions.py
index 5a03b52..08ce7b8 100644
--- a/tests/test_simple_functions.py
+++ b/tests/test_simple_functions.py
@@ -1,6 +1,6 @@
 import pytest
 
-from simple_functions import my_sum
+from simple_functions import my_sum, factorial
 
 
 class TestSimpleFunctions(object):
@@ -14,3 +14,13 @@ def test_my_add(self, iterable, expected):
         '''Test our add function'''
         isum = my_sum(iterable)
         assert isum == expected
+
+    @pytest.mark.parametrize('number, expected', [
+        (5, 120),
+        (3, 6),
+        (1, 1)
+    ])
+    def test_factorial(self, number, expected):
+        '''Test our factorial function'''
+        answer = factorial(number)
+        assert answer == expected