diff --git a/README.md b/README.md
index d06ecd3..7bf4ea7 100644
--- a/README.md
+++ b/README.md
@@ -41,3 +41,4 @@
 59 / 2 = 29
 24 * 33 = 792
 64 * 62 = 3968
+28 - 56 = -28