Q, add an "X" after the ID number to indicate whether it is a man or a woman.

There is an "X" behind the ID number, so it is impossible to tell whether it is a man or a woman.

The number 18 (the last digit) of the ID number represents the check code, which is obtained according to the calculation formula and used to check the correctness of the ID card. When the calculation result is 10, it is represented by x, and it is not judged whether it is male or female. 17 This number represents men and women, odd numbers represent men and even numbers represent women.

The check code is calculated by the numbering organization according to a unified formula. If someone's tail number is 0-9, X will not appear, but if the tail number is 10, then X must be used instead, because if 10 is used as the tail number, then this person's ID card will become 19, and the number of 19 violates the national standard. X is the Roman numeral 10. Replacing 10 with X can ensure that the citizen ID card meets the national standards.

Extended data:

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18 digit ID number arrangement rules:

1, the first 1, 2 digits.

Save the code.

2. Third and fourth place

City code.

3. Fifth and sixth place

District code.

4. Position 7~ 14

Date of birth.

5. Location 15 and 16

The code of the local police station.

6.No. 17

Odd numbers represent men and even numbers represent women.

7.No. 18

Check code: Some say it is a personal information code, which is generally randomly generated by a computer to check the correctness of the ID card. The check code can be a number from 0 to 9, sometimes represented by X.

References:

Baidu Encyclopedia-Resident ID Number