When you mention the number on the back of a credit card, it actually refers to the credit card’s CVV code, also known as the security code. This is located behind the signature line of your credit card and has a total of seven digits, the last three of which are key identifiers for the security of your card. In order to protect the safety of cardholders, banks strictly stipulate that the validity period and CVV code of credit cards cannot be inquired. The main function of the CVV code is to verify the identity of the cardholder to prevent fraudulent transactions. To ensure account security, these three digits must be kept strictly confidential.

The CVV code is usually visible on the back of the credit card and can be viewed by simply flipping it over. If your card is scratched and cannot be seen, and you really need to use it, the best solution is to contact your bank customer service directly. They can assist you with the card replacement process and ensure you get a new credit card with complete information. Remember, it's important to protect this personal information.