What does the last digit of the ID card mean?

The last digit of the ID card is the check code of the ID card number, also called the check digit. It is obtained from the previous 17 digits through certain arithmetic operation, which is used to check whether the ID number is legal.

The parity bit is calculated by multiplying the first 17 bits by the corresponding coefficients, then adding the products and dividing them by 1 1 to get the remainder. Finally, the parity bit value is determined according to the size of the remainder. The specific rules are as follows:

If the remainder is 0-9, the parity bit value is the remainder itself.

If the remainder is 10, the value of the parity bit is the letter X.

For example, the ID number is 32072419871201312x, and the last digit is the check bit. Through the operation of the first 17 digits, the remainder is 3. According to the above rules, the parity bit value is 3, so the complete ID number is 320724198712013123.

The check code of the ID number is a means to prevent the ID number from being tampered with or misused, and it is also a part of the ID number, which records personal identity information together with other information.