More than that, in the case of cards that use the credit card numbering system, instead of just ordinary bank cards, the number itself is algorithmically genera

More than that, in the case of cards that use the credit card numbering system, instead of just ordinary bank cards, the number itself is algorithmically generated and the last 4 digits (specifically the very last one) act as a kind of hash check (https://en.wikipedia.org/wiki/Luhn_algorithm https://en.wikipedia.org/wiki/Luhn_algorithm). Not that police or cashiers are likely to know that.