Monday, 26 December 2011

The Logic Behind a Credit Card Number

Any credit card or a debit card has a 16 digit number that’s unique in the world. But did you know these are not just random string of numbers but it reveal a little more than you think.

The first six digits of the credit card number is known as the Issuer Identification Number and this is to identify the institution that issued the card. VISA cards follow the series 4xx while MasterCard uses 51-55 as the prefix.

The first digit of the card represents the category of industry which issued your credit card. Taking away the 6 identifier digits and 1 check digit leaves the 9 digits in the middle that form the “account number”. and the last digit of the 16 is known as the “check digit” which is generated in such a way as to satisfy a certain condition.

Below is a visual illustration on how one can verify if a given credit card number is valid or not using simple addition.

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