# How To Manually Validate a Credit Card Number Using Simple Math

Do you want to make sure if a credit card number is genuine or not? You can easily verify a credit card’s validity using simple math.

Actually the credit card number is not just a random string of numbers, but it follows a specific rule (Luhn algorithm) and you can check if a credit card is valid or not using this algorithm.

## Validate a Credit Card With Simple Math

1. First note down the credit card number on a piece of paper.

2. Starting with the second digit from right, double every alternate digit and note it down under the original number. Cross the remaining digits.

3. While doubling the alternate digits in Step 2 above, If you got any number with two digits, then add those two digits together to make it a single digit. For instance, if your doubled 6 to get 12. Make it 3 (2+1).

4. Now add all the (uncrossed) digits together.

If the final sum ends in 0, then its a valid credit card number, otherwise its fake.

Check the interactive demo below that demonstrates the detection of a fake credit card using the simple math method explained above.

If you have any problem in understanding the procedure to validate a credit card number manually, then either post your question using the comments form below or try credit card checker.