Why is the last digit of some people's ID card X?

I used to transfer files when I went to college. When I first saw that my ID card was X, I thought to myself, this person is really rigorous, and the last one is confidential, so I also wrote the last one as X because I am smart. The result was very sad, the number was wrong, and a big joke was made.

There are still many fate test questions. According to the last person on the ID card, you can see your fortune. So does X indicate that they are all future Ma Yun and Niu X?

Haha, it's all just entertainment.

So what does the last X of the ID card mean? The resident ID card consists of 18 digits, and the first 6 digits are administrative division codes, in which 1-2 is the provincial code, 2-4 is the city code and 5-6 is the county code. Bits 7 to 14 are your birth date code, bits 15 to 17 are serial codes, and bits 18 are check codes calculated according to the previous bits 17. If the suffix is 0-9, there is no X. If it is 10, it is replaced by X. This can ensure that the ID card is 18, not 19.

Some friends will ask if it is inconvenient to bring X, of course not. It doesn't matter. The last digit is from 0- 10, which is an eleven-digit number of * *, that is to say, about 9% of our compatriots in the country take X as the last digit. If you usually need to enter your student status, open a bank account, buy tickets online, etc., when you need computer admission, just write the last digit as a capital letter X.

So let's face up to this poor X, it won't affect our normal life. Maybe this will be your lucky letter.