diff --git a/README.md b/README.md
index 1ec0bba..e715af5 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,2 @@
 # CI MPM
-Toy repo for CI lecture.
+Toy repo with some simple functions for the CI lecture
diff --git a/simple_functions/functions1.py b/simple_functions/functions1.py
index 8c63a4d..c584711 100644
--- a/simple_functions/functions1.py
+++ b/simple_functions/functions1.py
@@ -1,5 +1,6 @@
-
-__all__ = ['my_sum']
+from functools import cache
+import functools
+__all__ = ['my_sum',"factorial"]
 
 
 def my_sum(iterable):
@@ -7,3 +8,6 @@ def my_sum(iterable):
     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..83184a5 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 +14,12 @@ 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
\ No newline at end of file