diff --git a/README.md b/README.md
index 62b3e98..4f6a3e9 100644
--- a/README.md
+++ b/README.md
@@ -41,3 +41,4 @@
 45 - 7 = 38
 22 * 40 = 880
 37 / 1 = 37
+91 - 87 = 4