There are 7 digits in the credit card signature field, the last 3 digits are the only ones.

The last three digits are called the CVV code, which is found on every card and is also the cardholder’s identification code.

CVV is Card Verification Value, while Mastercard is called Card Validation Code (CVC).

VISA CVV and MC CVC are both 3-digit or 4-digit numbers generated by the card number, validity period and service constraint code. They are generally written in the 2-track user-defined data area of ??the card's magnetic stripe. The generation methods of CVV ??and CVC are the same, but they are called differently. CVV2 is a number printed in the signature area of ??a Visa/MasterCard card. It is the 3 digits after the credit card number. The last three digits we usually see on the back of credit cards are actually CVV2, not the CVV code.