\u00a0number is the check digit. Check digits are used for card validation, security purposes, and the detection of typos. On Visa cards, the check digit is the 16th digit, while it’s the 15th digit on American Express cards.<\/span><\/p>\nCard networks run the check digit and the preceding digits through the Luhn Algorithm, a simple checksum formula, to validate the card number and reduce fraud.<\/span><\/p>\n<\/span>What is the security code on a Visa card?\u00a0<\/span><\/strong><\/span><\/h2>\nThe security code on a Visa card is the three-digit number located on the back of the card, near the signature strip. This code, called a Card Verification Value (CVV), verifies that the card is genuine and has not been tampered with. The CVV code helps to protect businesses against card fraud by verifying that the card is in the possession of the person who is using it.<\/span><\/p>\n<\/span>Free card validator tool: Verify a card number<\/span><\/strong><\/span><\/h2>\nOur free card validator tool is designed to check whether a debit card number is valid. Simply enter the card number, and the tool will tell you whether the card is valid or not.<\/span><\/p>\n