Over the years, countless people have looked at 16-digit credit card numbers and said things like “Why do they need so many numbers? It’s not like there are 9.999 quadrillion bank accounts out there.” Well, that’s true. But the numbers on your card aren’t just about how many accounts or cardholders exist. They also indicate information about your card issuer, its network and tells processors whether or not the number is valid. [More]
