<?php
function check_rnn($rnn)
{
if (is_numeric($rnn) && strlen($rnn)==12 && substr_count($rnn, $rnn[0])<12) {
$weight = array(1,2,3,4,5,6,7,8,9,10,1);
$i=0;
do {
for ($s=0, $razr=0; $razr<11; $razr++) $s += $rnn[$razr] * $weight[$razr];
$k = $s%11;
array_push($weight, array_shift($weight)+1);
} while ($k>=10 && ++$i<10);
return ($k == $rnn[11]);
}
return false;
}
$rnn = "600500007425";
var_dump(check_rnn($rnn));
?>