diff --git a/README.md b/README.md
index e7f434e..edcb41d 100644
--- a/README.md
+++ b/README.md
@@ -41,3 +41,4 @@
 57 / 9 = 6
 36 + 75 = 111
 72 / 8 = 9
+11 - 20 = -9