Simple calculator, which can perform basic mathematical operations by menu driven using Linux shell script in Ubuntu

echo 1.Addition
echo 2.Subtraction
echo 3.Division
echo 4.Multiply
read op
result=0
if [ $op = 1 ]
then
echo Enter Num1
read num1
echo Enter Num2
read num2
result=`expr $num1 + $num2`
fi
if [ $op = 2 ]
then
echo Enter Num1
read num1
echo Enter Num2
read num2
result=`expr $num1 - $num2`
fi
if [ $op = 3 ]
then
echo Enter Num1
read num1
echo Enter Num2
read num2
result=`expr $num1 \/ $num2`
fi
if [ $op = 4 ]
then
echo Enter Num1
read num1
echo Enter Num2
read num2
result=`expr $num1 \* $num2`
fi
echo Your Answer Is :-"$result"