Simple Calculator

Algorithm
Step 1 : Start
Step 2 : Read operands a and b
Step 3 : Display operation menu
Step 4 : Read option
Step 5 : If option = 1 then
Calculate c = a + b
Step 5.1 : else if option = 2 then
Calculate c = a – b
Step 5.2 : else if option = 3 then
Calculate c = a * b
Step 5.3 : else if option = 4 then
Calculate c = a / b
Step 5.4 : else if option = 5 then
Calculate c = a % b
Step 5.5 : else
Print "Invalid option"
Step 6 : Print c
Step 7 : Stop

Program (calc.sh)
# Arithmetic operations--multiple statements in a block
echo -n "Enter the two numbers : "
read a b
echo " 1. Addition"
echo " 2. Subtraction"
echo " 3. Multiplication"
echo " 4. Division"
echo " 5. Modulo Division"
echo -n "Enter the option : "
read option

case $option in
1) c=`expr $a + $b`
echo "$a + $b = $c";;
2) c=`expr $a - $b`
echo "$a - $b = $c";;
3) c=`expr $a \* $b`
echo "$a * $b = $c";;
4) c=`expr $a / $b`
echo "$a / $b = $c";;
5) c=`expr $a % $b`
echo "$a % $b = $c";;
*) echo "Invalid Option"
esac

Output
[vijai@localhost multway]$ sh calc.sh
Enter the two numbers : 2 4
1. Addition
2. Subtraction
3. Multiplication
4. Division
5. Modulo Division
Enter the option : 1
2 + 4 = 6