diff --git a/factorial.py b/factorial.py
index 3569741..611e1a6 100755
--- a/factorial.py
+++ b/factorial.py
@@ -7,17 +7,23 @@
 
 
 def factorial(n):
-    # TODO Define your logic for factorial here
-    return # TODO!
+    if n == 0:
+        return 1
+    else:
+        return n*factorial(n-1)
+
 
 def test_factorial():
     assert factorial(1) == 1
-    # TODO: add more
+    assert factorial(0) == 1
+    assert factorial(2) == 2
+    assert factorial(3) == 6
+
 
 if __name__ == '__main__':
     # This is a way to determine either file was "executed", so if it was
     # imported (by e.g. pytest) as a library, we should not run code
     # below
-    nconditions = raw_input("Please enter number of conditions: ")
+    nconditions = input("Please enter number of conditions: ")
     norders = factorial(nconditions)
-    print("Number of possible trial orders: " + str(norders)
+    print("Number of possible trial orders: " + str(norders))