I'm wondering why echoing $total in this Bash script doesn't show up as anything? In theory it should show up as the total of all the files in the folder, but it just returns blank.

#!/bin/bash
ls -l $1 |
while read file_parm
do
        size=`echo $file_parm | cut -f 5 -d " "`
        let "total += size"
        echo $size
done 
echo "The total size of the files in the directory <$1> is:"
echo $total