diff --git a/README.md b/README.md
index d241c4c..30a09a3 100644
--- a/README.md
+++ b/README.md
@@ -42,3 +42,4 @@
 96 - 21 = 75
 57 / 3 = 19
 33 * 62 = 2046
+81 - 81 = 0