protected function crap($ccn, $coverage)
{
if ($coverage == 0) {
return (string) (pow($ccn, 2) + $ccn);
}
if ($coverage >= 95) {
return (string) $ccn;
}
return sprintf('%01.2F', pow($ccn, 2) * pow(1 - $coverage / 100, 3) + $ccn);
}