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Meaning of Numbers On A Debit Or Credit Card

Credit-Debit-Card I was going through the articles written so far on Knowledge Hub, when I came across the one which explained the meaning of numbers at the bottom of a cheque. Reading it made me wonder if the numbers written on a credit/debit card also have some particular meaning. So I decided to pursue this topic in detail, and as I guessed, each of these digits has a specific meaning.

Note: Since VISA and MASTER Cards are the most widely available cards, I have used them for my research. But the results hold true for all card types.


Identifying Card Issuer Type

The first digit in a card represents the Major Industry Identifier and is known as MII digit. It represents the category of entity which issued your credit card. There are following types of issuers:

MII Digit

Issuer Type


ISO/TC 68 and other industry assignments




Airlines and other industry assignments


Travel and entertainment (such as American Express and Diners Club)


Banking and financial (Visa)


Banking and financial (MasterCard)


Merchandizing and banking (Discover)




Telecommunications and other industry assignments


National assignment

You can understand this better by taking out your card and seeing the first digit. If you own a petroleum card (such as those issued by Exxon Mobil or BP) then your card number will start with 7. If you own a debit/credit card issued by a bank then it will start with 4 or 5 (depending on whether it is a Visa card or Master card).

Identifying Card Issuer

The first six digits in a card represent the issuer and is known as Issuer Identification Number (IIN). Below is a list of popular card issuers and their corresponding code:



American Express

34xxxx, 37xxxx



Master Card


So if you have a card that starts with 51 that means it is a Master Card.
Note: During my study I observed that Maestro card starts with 50 and 62. If you know something about Maestro cards, please share it through your comments.

Mathematically speaking, there can be 10 raised to power 6 (since 6 digits are used to identify an issuer), i.e. 1 million unique card issuers !!

Finding Account Number

Starting from the seventh digit to second last digit, i.e., 7th to n-1 digit in a card represents the account number. I noticed that this account number is not the same as your bank account number. For cards issued by ICICI (whether VISA or MASTER Cards), only first five digits of the card number and the account number matched, while there was no such similarity for cards issued by HDFC bank.

Conclusion: 7th to n-1 digit in the card represents the account number. This account number is not the account number of your bank but the account number generated by the Card Issuer (such as VISA or Master Card) to uniquely identify you.

A card can have a maximum of 19 digits. So the account number can be a maximum of 12 digit number. That means each issuer can issue a maximum of 10 raised to the power 12, i.e., 1 trillion cards !!

Check Digit

The last digit on the card is known as the check digit and it determines whether it is a valid card or not.

With that we come to an end on this interesting discussion about the numbers written on a debit or credit card. The next article will be even more interesting, because there we’ll see the check digit in action. We’ll find how the check digit is used to determine if the card is valid or not. We’ll also understand the reason behind having such long card numbers. So if you have not already subscribed to Knowledge Hub, I’ll advise you to do it now, so that you don’t miss the article.

In the mean time you can read the article about the meaning of numbers written at the bottom of a cheque, and if you want to understand other banking terms then I’ll suggest you to read the article on repo, reverse repo, crr, slr and bank rate.

This article has been written after a lot of research and took a lot of time, so retweets, fb share and your feedback will be greatly appreciated.

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