ID number (last digit.

Why is the last digit of my ID card X? In the mandatory national standard gb120043 citizenship numbers, there are clear provisions on citizenship numbers. Currently, there are 18 ID card numbers, each of which has a clear meaning. In the order from left to right, the first six digits are called "address codes", indicating the administrative divisions of the county (city, flag, district) where the resident account is located.Code. This part is encoded according to GB/t2260 "Administrative Division Code of the People's Republic of China. Generally, the address code indicates the place of birth. The next eight digits are called "birthdate code", indicating the year, month, and day of birth. The next three digits are called "sequence codes", which are the sequence numbers assigned to the first 14 digits with the same numbers. The odd numbers are allocated to men and the even numbers are allocated to women. The preceding 17 characters are collectively referred to as ontology codes, which are directly determined by my personal information. The last digit is the verification code. Verification code using iso7064: 1983, MOD11-2 verification code system, is based on the validation formula, determined by the body code, used to verify the accuracy of the input or transcription process. Verification formula requirements: In the order from right to left, multiply the first digit (I .e. the Verification Code) on the Right by 1, the second digit by 2, the third digit by 4, and so on, each left digit is multiplied by 2. Then the sum of the 18 products is required to be divided by more than 1 in 11. You can easily obtain the verification code based on the verification formula. First, sum the other 17 products and divide them by 11 to obtain the remainder. Then subtract the remainder from 1 or 12 to get the verification code. Because the remainder is obtained by dividing by 11, when the verification code is calculated as 10, it is represented by the appropriate number X. This is why the last digit of some people's ID card numbers is X.