count to one million script

#!/bin/bash
# Count to one million script (for forum games)
# This script is contributed to the public domain with CC0.
# See https://creativecommons.org/publicdomain/zero/1.0/legalcode for more info.

# Checks if command line options are missing.
if [[ $1 = "" ]]; then
    echo "Usage: `basename $0` [NUMBER]..."
    exit 1;
fi

let "NUMBER = $1"
QUITHANDLER=0
END=1

while [[ $QUITHANDLER -lt $END ]]
do
let "REMAINING = 1000000 - $NUMBER"
echo "$NUMBER

(Only $REMAINING to go!)"  | xsel -b -i

echo "Copied to clipboard ($NUMBER) Press enter to repeat.
Type any number greater than 0 to quit."

read QUITHANDLER
let "NUMBER++"
done