diff --git a/README.md b/README.md
index 6a7dfdd..cf8e10a 100644
--- a/README.md
+++ b/README.md
@@ -41,3 +41,4 @@
 58 - 87 = -29
 95 + 66 = 161
 99 + 67 = 166
+67 - 80 = -13