SHELL Script Function

 echo "enter two numbers:"
read a
read b
add()
{
c=expr $a + $b
echo "addition is $c"
}
sub()
{
c=expr $a - $b
echo "sub is $c"
}
mul()
{
c=expr $a * $b
echo "Multiplication is $c"
}
div()
{
c=expr $a / $b
echo "division is $c"
}
Add sub mul div