php随机取出各个位上的数字

<?php
$a=mt_rand(0,123456789);
$num=$a;
$num1=$num%10;
$num=($num-$num1)/10;
$num2=$num%10;
$num=($num-$num2)/10;
$num3=$num%10;
$num=($num-$num3)/10;
$num4=$num%10;
$num=($num-$num4)/10;
$num5=$num%10;
$num=($num-$num5)/10;
$num6=$num%10;
$num=($num-$num6)/10;
$num7=$num%10;
$num=($num-$num7)/10;
$num8=$num%10;
$num=($num-$num8)/10;
$num9=$num%10;

echo "随机数是：{$a}<br>";
echo "亿位是{$num9}/t";
echo "千万位是{$num8}/t";
echo "百万位是{$num7}/t";
echo "十万位是{$num6}/t";
echo "万位是{$num5}/t";
echo "千位是{$num4}/t";
echo "百位是{$num3}/t";
echo "十位是{$num2}/t";
echo "个位是{$num1}/t";
?>