The last digit of the ID number represents the check code, which is used to check the correctness of the ID card. The check code can be a number from 0 to 10, and 10 is represented by X. Because if the tail number is used for 10, the identity card will become 19, while the 19 digit number is against national standard, and the computer application system in China also does not recognize 19 ID number. X is the Roman numeral 10. Replacing 10 with X can ensure that citizens' ID cards meet national standards.
The ID number is the only and lifelong identity code compiled by People's Republic of China residents since the date of applying for residence permit. It is widely used by citizens in People's Republic of China to handle matters related to politics, economy, social life and other rights and interests. The official title should be "citizenship number".
Citizenship number is a feature combination code, which is composed of 17 digit ontology code and one digit verification code. The sequence from left to right is: six digit address code, eight digit date of birth code, three digit sequence code and one digit check code.
Validity period of ID card:
The validity period of resident ID card is divided into five years, 10 years, 20 years and long-term. For those under the age of 16, a resident identity card valid for 5 years shall be issued; For those aged 16 to 25, a resident identity card valid for 10 years shall be issued; A resident identity card valid for 20 years shall be issued to those aged 26 to 45; Those over the age of 46 shall be issued with long-term valid resident identity cards. The validity period of the certificate shall be calculated from the date of issuance.