The check code is a unified check code calculated according to the first 17 bits of the 18-bit ID card and a unit check code compiled according to the number. The verification code is from 0- 10. However, since 10 is a two-digit number, which violates the national standard of 18 digits, the Roman number X is used instead of the number 10 to ensure that the citizen ID card meets the national standard.
Credit card security code is a security code for online or telephone transactions. Generally, it is a 3-digit or 4-digit number printed on a credit card, and the printing position of different types of cards will be different. It is usually used to prove that the payer has a credit card at the time of transaction, thus preventing credit card fraud. For the location of credit card security code, the location of credit card security code of different card organizations is also different. Card security codes issued by UnionPay, JCB, MasterCard and VISA are printed on the last three digits of the signature column on the back of the credit card.
Ensure that the last three digits of the credit card:
1. Take care of your credit card and don't lend it to others casually. In daily credit card consumption, you can also cover the last three yards with opaque tape;
2. Once you find that your credit card is lost or you receive an abnormal transaction information notice, call the bank to report the loss or temporarily freeze your account as soon as possible to avoid the loss of funds;
3. If the credit card usually does not involve large transactions, it is best to set a transaction limit to avoid the risk of huge amounts of stolen credit;
4. Don't enter some illegal or unsafe websites, and don't fill in your credit card information and personal information casually on these websites.