php 1-100之間能被3整除的數字之和;

<?php
//1-100之間能被3整除的數字之和;
$n =1;
$sum = 0;
$m = 0;
while($n<=100){

    if($n % 3 == 0)
    {
        // echo  $n.'<br>';//每個數都循環出來
        $sum += $n;
    }

    $n++;

}
echo $sum;

?>