How many of you know what credit card numbers really mean? Those 16 digits are there for a reason and they aren’t random. Knowing what they stand for will give you some useful information about a credit card, not the least of which is whether the card is fake or not.

Here’s an info graphic of “Luhn” or “Mod 10″ formula from mint.com

However, the Luhn formula validates just the credit card number, it does not necessarily mean that it also validates the expiry date and card security code (CVV, CVC). For those who have a fake credit card which complies with the Luhn check, it will proceed through the transaction end, and the primary card company will surely catch the mischief-maker. That being said, don’t go about attempting to use these credit card numbers to purchase any items you’re interested in.

Paypal has readily made Test Credit Card Account Numbers website, to help people who don’t want to do the math. Enjoy!