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What algorithm is used to validate credit card number?

To validate a credit card number, the most widely used algorithm is the Luhn algorithm.

What is Luhn algorithm?

The Luhn algorithm is like a quick check to make sure a number (like a credit card number) is typed in correctly. Here’s how it works in three easy steps, using a pretend credit card number as an example:

Example Credit Card Number: 1234 5678 9123 4560

Double Every Other Number:

Start from the second-to-last digit, moving left, and double every other number. Our example becomes: 1-4-3-10-5-14-9-4-1-6-3-10-4-10-6-0 Add Digits Together:

If doubling a number makes it two digits, add those digits together to get a single number (e.g., 10 becomes 1+0 = 1). Then, add all these numbers up. For our example: 1+4+3+1+5+5+9+4+1+6+3+1+4+1+6+0 = 44 Check If Total Is Divisible by 10:

If the total sum is a multiple of 10 (like 30, 40, 50), the number passes the check. It's a quick way to spot mistakes. Our example's total is 44, which is not divisible by 10, so this would indicate a problem or typo in the number we used. Remember: This is just a made-up example to show how the steps work. Real credit card numbers are set up to pass this test, helping to catch simple mistakes like typing errors.