public function validate($vatNumber)
{
if (strlen($vatNumber) != 10) {
return false;
}
$weights = array(6, 5, 7, 2, 3, 4, 5, 6, 7);
$checksum = (int) $vatNumber[9];
$checkval = $this->sumWeights($weights, $vatNumber);
if ($checkval % 11 != $checksum) {
return false;
}
return true;
}