Living in the U.S. without a credit card is close to impossible and most of us probably carry more than one card around with us at all times. But what do you actually know about your card? The good folks over at Mint.com put together a nice little infographic that explains what those numbers on your card really mean.

In case you thought these numbers were random, think again. And if you need a quick math challenge while you are checking out at the supermarket, the infographic also teaches you a little trick to see if your card is valid.

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