php random number
// $min and $max are optional
rand($min,$max);
php random number
rand();
php random 5 digit number
$limit = 3;
echo random_int(10 ** ($limit - 1), (10 ** $limit) - 1);
php randon integer 4 digit
$digits = 3;
echo rand(pow(10, $digits-1), pow(10, $digits)-1);