#!/bin/bash
let "add=$1+$2"
let "sub=$1-$2"
let "mul=$1*$2"
let "div=$1 / $2"
power=1

for ((c=0;c<$2;c++))
        do let "power=$power*$1"
        done

case $3 in
        '+') echo "$add";;
        '-') echo "$sub";;
        "/") echo "$div";;
        '^') echo "$power";;
        *) echo "$mul";;
esac