Online PHP editor | refs for dgr1M

@ 2015-07-07T21:29:55Z

<?php

$v = '10155674128355111';

echo $v % 6 . PHP_EOL;

while (strlen($v) > 9)
{
    $short = substr($v, 0, 9);
    
    $prefix = (int)$short % 6;
    
    $v = $prefix . substr($v, 9);
    
    echo "SHORT: ". $short . "  PREFIX: ". $prefix . " NUMBER: ". $v . PHP_EOL;
}

echo $v % 6;