What Do Credit Card Numbers Mean?


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Credit card numbers each serve a particular function. It may be hard for you to believe, but they are not just random identification numbers. They determine how each transaction will be routed and enhance security.

You probably know a few credit card fun facts and memorised your own credit card numbers by heart, either in full or the last four digits. You have recited them more times then you can count, but if you are like most people you probably have no idea what they mean. The numbers each have a specific identification function either for the bank, the system or you personally. While it is not imperative to spending that you know what the numbers mean it is food for though that helps you understand the process your information goes through with each credit card transaction.

Unlike other account numbers like those of the gas or phone company or even department stores, credit cards all use the same number system. Almost all national credit card numbers are based on the ANSI Standard X4.12-1983 system. In this system the number and structure of the numbers on the card indicate what kind of card it is and to whom it belongs.

Credit card numbers breakdown

  • The first number on your credit card notes the system that your card belongs to. Each of the major credit cards are assigned to a system.
    • Number 6 denotes a Discover credit card
    • Number 5 denotes a Mastercard
    • Number 4 denotes a Visa
    • Number 3 denotes a travel or entertainment card like American Express or Diners Club
  • Within each system is a structure that is unique to that credit card company. For example:
    • On American Express cards the third and fourth digits are type and currency, the fifth through the eleventh digits are the account number, the twelfth through the fourteenth digits are the cards number within that particular account, and the fifteenth digit is the check number.
    • A Visa uses digits two through six for the bank number, the seventh digit through the twelfth or the fifteenth are the account number and digit thirteen or sixteen is the check number.
    • Mastercard uses digits two through six as account numbers depending on the length it can be digits two and three or two through four or two through five or six. After the bank number the digits that follow up to the fifteenth are the account number and the sixteenth digit is the check number.

While it is more important to know where you are spending your money then the function of your credit card numbers it is helpful to understand the complexities of the credit card system. Once you realise how much effort has gone into ensuring security and efficiency you will have more appreciation for your card.

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