"; echo $a+5; echo "
"; echo "
"; echo "減法
"; echo ($a-5).'
'; //html顏色：https://www.w3schools.com/html/html_colors.asp echo "
"; echo "乘法
"; echo ($a*5).'
'; echo "
"; echo "

除法


"; echo ($a/5).'
'; echo "
求餘數
"; echo ($a%3).'
'; ?>