Your card number is carefully structured. The very first digit is what’s known as the major industry identifier. A 4 means ...

How to Validate Credit Card Information. Credit card numbers are generated according to a specific set of rules. This gives merchants a way to verify the validity of a card number prior to ...

All mainstream credit card numbers obey a mathematical trick designed to catch the most common typos. It’s called the Luhn algorithm, named after IBM researcher Hans Peter Luhn, who patented it in ...