CardCheckDigit

Credit Card Validation - Check Digits Algorithm

A check digit is a digit added to a number (mostly at the end) that validates the authenticity of the card number.

Possible uses for this information:

1. When a user has keyed in a credit card number (or scanned it) and you want to validate it before sending it our for debit authorization.
2. When issuing cards, say an affinity card, you might want to add a check digit using the MOD 10 method.