n的阶乘末尾出现的次数

<?php
function  find($n){
        $count = 0;
           $j = 0;
        for($i = 5; $i <= $n; $i = $i + 5){
            $j = $i;
            while($j % 5 == 0){
                $count ++;
                $j /= 5;
            }
        }
        return $count ;
    }
    $a = find(5);
    var_dump($a);