A credit card number must be from 13 to 16 digits long. The last digit of the number is the check digit. That number is calculated from an algorithm (called the Luhn formula or MOD 10 ) on the other numbers. This is to spot typo…
I’ve been working on an e-commerce system recently (as you may have been able to guess) and to test the credit card integration side of things, I needed some test credit card details of “valid looking” card numbers… I eventually …
