diff --git a/advanced/learning_bash_scripting.md b/advanced/learning_bash_scripting.md
index c81bb08..b8b7395 100644
--- a/advanced/learning_bash_scripting.md
+++ b/advanced/learning_bash_scripting.md
@@ -1227,7 +1227,7 @@ waldek@debian:~$
 #!/bin/bash
 
 difficulty=100
-computernumber=$(( "$RANDOM % $difficulty"))
+computernumber=$(( $RANDOM % ( $difficulty + 1)))
 echo "I have a number in mind between 0 and $difficulty"
 
 while true; do