Credit Card Number Explanation

3 Credit Card Data Format Components to Know. A credit card number, for example 1234567812345678, consists of three parts:

1. The bank identification number (BIN): The first six digits are the bank identification number (BIN) or issuer identification number (IIN). This string of numbers identifies the issuer of the card.

2. The account number: The number between the bank identification number and the check digit is six to nine digits long and is used to identify the individual account number.

3. The check digit: The last digit is the check digit and is added to validate the authenticity of the credit card number (based on the Luhn algorithm).

The Luhn algorithm for the checksum is an interesting calculation! For those interested:

Luhn algorithm by hand includes a few different steps. They include the following.

1. Write down the credit card number: e.g., 4417 1234 5678 9113

2. Starting from the first number, double every other digit. 4(x2) 4 1(x2) 7 1(x2) 2 3(x2) 4 5(x2) 6 7(x2) 8 9(x2) 1 1(x2) 3

The doubled numbers result in: 8 2 2 6 10 14 18 2

3. If the result of the doubling ends up with a two digits, then add those two digits together: 10 = 1+0 14= 1+4 18= 1+8

4. Add up all numbers: 8+4+2+7 + 2+2+6+4 + 1+0+6+1+4+8 + 1+8+1+2+3 = 70

If the final sum is divisible by 10, then the credit card is valid. If it is not divisible by 10, the number is invalid or fake. In the above example, credit card number 4417 1234 5678 9113 has passed the Luhn test.