diff --git a/README.md b/README.md
index 287b97f..6654d5d 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,7 @@ Add the following to cron to automate Backup
 <br>
 
 Edit the file zip_folder_daily.sh `(If you used automatic install it's in /opt)` and change the day number in line 16.
+- If you want 30 days, it's '30 - 1', so '29'
 > find "${ARCHIVE_DIR}" -name "folder_*.zip" -mtime +`13` -exec rm {} \;
 
 </details> 
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