Script to display sum of two number and to do calculations such as +, -, / etc

#!/bin/bash
# Script to display sum of two number and to do calculations such as +, -, / etc
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# ----------------------------------------------------------------------
echo "**** My calculator ****"
echo "M A I N - M E N U"
echo "1. Multiplication"
echo "2. Subtraction"
echo "3. Remainder"
echo "4. Divide"
echo -n "Please select your choice (1-4) : "
read choice
 
echo -n "Enter your first number : "
read n1
echo -n "Enter your second number : "
read n2
 
if [ $choice -eq 1 ]
then
	answer="$n1 x $n2 = $(( $n1 * $n2 ))"
elif [ $choice -eq 2 ]
then
	answer="$n1 - $n2 = $(( $n1 - $n2 ))"
elif [ $choice -eq 3 ]
then
	answer="$n1 % $n2 = $(( $n1 % $n2 ))"
elif [ $choice -eq 4 ]
then
	answer="$n1 / $n2 = $(( $n1 / $n2 ))"
else
	echo "Sorry please select number between 1-4 only"
	exit 1
fi
echo $answer