Program in UNIX to reverse the entered number.

Write a shell script to reverse the entered number.(e.g. if user enters the number 123 then the output will be 321)
echo -n "Enter number :"
read n
sum=0
while [ $n -ne 0 ]
do
rem=`expr $n % 10`
n=`expr $n / 10`
sum=`expr $sum \* 10 + $rem`
done

echo "Reverse number is $sum"