diff --git a/README.md b/README.md
index 15b3aad..25f9318 100644
--- a/README.md
+++ b/README.md
@@ -41,3 +41,4 @@
 30 * 20 = 600
 36 * 52 = 1872
 15 / 1 = 15
+89 - 8 = 81