$code = $_POST['code'];
$rand1 = rand(0, 9);
$rand2 = rand(0, 9);
$rand3 = rand(0, 9);
$rand4 = rand(0, 9);
$rand5 = rand(0, 9);
$rand6 = rand(0, 9);
$totalrand = $rand1.$rand2.$rand3.$rand4.$rand5.$rand6;
if($code == $totalrand)
{
//....
}
else
{
//....
}