# Luhn Algorithm Calculator

The Luhn algorithm is used to validate various identification numbers, such as the **numbers on the front of credit cards, social security numbers or the IMEI of a phone**.

The last number of a Luhn sequence is the **control digit**. If you enter a digit incorrectly, therefore the algorithm will calculate a different checksum. So, the Luhn algorithm is well suited for checking numbers entered by people. In case they have a typo in their sequence, then the last digit will fail the validation.

If you want to see the validation method, take a look at this answer.