Linux substring & if

#!/bin/bash -x
. $HOME/.bash_profile
var=POJ_2 
versionNumber=${var:4:1} 
 if [ "$versionNumber" = "1" ]; then 
    echo "Project 1"
elif [ "$versionNumber" = "2" ]; then
    echo "Project 3"
else
 echo "sorry I don't know!"
 exit 0
fi