shell兩數之間的算術運算

#!/bin/bash
read -p "請輸入第一個數：" a
read -p "請輸入第二個數：" b
echo "$a+$b=$[$a+$b]"
echo "$a-$b=$[$a-$b]"
echo "$a×$b=$[$a*$b]"
echo "$a/$b=$[$a/$b]"
echo "$a%$b=$[$a%$b]"