Ah, I see
Ok, this is another question that cannot really be answered. Cards use different types of numbers, and it will depend on the card you have
For example, Visa cards start with a 4, Mastercard's start with a 5 (in the UK at least
).
Whichever card you use, enter the number as it appears on your card, entering it any other way will return an error
Regards.
DJM.