A credit card or a debit card has a unique 16 digit number that everyone is aware of. But, do you know these numbers are not a just random string of numbers rather it reveals a lot more information than you think.
Ever wondered what does numbers on credit card actually represents? How that 16 digits identify the bank and the account from which your money needs to be paid to the billing party?
A sample credit card
Let’s dive into these 16 digits that we just see a string of random numbers and is often wondering what numbers on credit card mean.
Major Identity Identifier (MII): The first digit of the card represents the category of industry which issued your credit card. This is known as “Major Industry Identifier” short for MII.
Following is the list of Major Identity Identifier MII:
Issuer Identification Number (IIN): The first six digits of the credit card number are known as the Issuer Identification Number short for IIN and this is to identify the institution that issued the card.
The series followed by VISA cards starts from 4xx while that of Mastercard starts from 51–55 as the prefix.
Account Number associated with Credit Card: Taking away the first 6 identifier digits, the following 6 to 9 digits constitutes unique bank account number. Now, this is not exactly the bank account number of a customer but the account number assigned to your credit account.
Check Digit: And lastly, one last digit known as the “check digit” which is generated in such a way as to satisfy a certain condition.
Step 1: Let’s consider the card number as 1802909582961827
Step 2: As of now, just consider first 15 digits i.e., 180290958296182|7
Step 3: Now beginning from the left, start with the first number, take every second number and multiply it by 2 as shown here:
Starting from the first i.e., 1 and taking every second number, we will get the following numbers: 1 0 9 9 8 9 1 2
1 * 2 = 2
0 * 2 = 0
9 * 2 = 18
9 * 2 = 18
8 * 2 = 16
9 * 2 = 18
1 * 2 = 2
2 * 2 = 4
Step 4: Sum up the digits if the multiplication results in a 2 digit number. i.e., 18 => 1 + 8 = 9
This will give us all the result in a single digit number.
So, we get : 2,0,9,9,7,9,2,4
Step 5: Now, Sum up all the single digits and all the digits left in the card number.
i.e., 2+0+9+9+7+9+2+4 + 8+2+0+5+2+6+8 = 73
Add the sum together. Now, what must be added to the sum obtained so that it is divisible by 10? In this case, it is 7
So, 73+ 7 = 80 which is divisible by 10.
This last digit so obtained is called as Checksum digit.
That’s the logic behind credit/debit card numbers.
Now, the number of digits in a credit card number varies with the issuing authority.
VISA and VISA Electron: 13 or 16 digits
Mastercard: 16 digits
Discover: 16 digits
American Express: 15 digits
Diners Club Card: 14 digits (including International and Blanche)
Maestro Cards: 12 to 19 (multi-national debit card)
Laser: 16 to 19 (Ireland)
Switch: 16, 18 or 19 (United Kingdom)
Solo: 16, 18 or 19 (United Kingdom)
JCB: 15 or 16 (Japan Credit Bureau: Japan)
China UnionPay: 16 (People’s Republic of China: China)
We perform some checks on your number and explain what each part of it means.
There is another number which is usually behind the card usually of 3 to 4 digits and is known by various names like CVVs, CVV2s called card verification value, and card security code (CSC). These are all calculated using the CVV algorithm.
The codes have different names as per issuing authority:
Code issued by issuing authority
They are required by payment systems such as MasterCard and Visa to authenticate their credit or debit cards.
There are several types of security codes:
To generate or calculate the 3-digit CVV, the algorithm requires is:
Primary Account Number (PAN), a 4-digit Expiration Date, a pair of DES keys (CVKs), and a 3-digit Service Code. This algorithm is only known to the bank and not for any person or organization.
This way it will be easier for you to call to cancel the cards if your purse or wallet is lost or stolen.
To verify any credit card or debit card click here.
In the next part of this series, we will see the implementation of the code that will generate valid credit/debit card numbers along with their Issuing Authority and Account Number.
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