Regarding the structure and generation rules of social security numbers (social security numbers), different countries and regions have different rules. The following is a description of major systems such as China and the United States (**Note: All sample numbers are fictitious and are only used for explanation**)： --- ### **1. Chinese Social Security Number (Citizenship Number)** China's social security number is the same as the citizenship number, it is **18 digits**, and the structure is as follows： ####**Structure decomposition** (example: `11010519800101001X`) | Part | Number of digits | Description | |------------|--------|----------------------------------------------------------------------| | ** Address code ** | The first 6 digits / correspond to the administrative division code of the place of household registration (such as`110105`=Chaoyang District, Beijing). | |**Date of birth**/Middle 8 digits |format is`YYYYMMDD` (e.g.`19800101'=January 1, 1980). | | ** Sequence code ** / The last 3 digits | the sequence number of people born in the same region or on the same day, the last odd number is male and the even number is female (such as `001`). | | ** Check code ** | The last 1 digit | is calculated from the first 17 digits, the range is `0-9' or'x` (Roman numeral 10). | ####**Check code calculation rules** 1. The first 17 digits are multiplied by the weight coefficient: `[7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2]`. 2. Divide the sum of the products by 11 to get the remainder. 3. Correspond to the check code according to the remainder: `[1,0,X,9,8,7,6,5,4,3,2]`（ The remainder 0 corresponds to `1`, the remainder 2 corresponds to `X`, and so on). --- ### **2. U.S. Social Security Number (SSN)** The Social Security Number (SSN) of the United States is **9 digits**, and the format is `AAA-GG-SSSS`： ####**Structure decomposition ** (example: `123-45-6789`) | Part | Number of digits | Description | |------------|--------|----------------------------------------------------------------------| | * * Area Number (AAA) * * | The first 3 digits | originally referred to the issuing area (for example, `123` may correspond to a certain state), but after 2011 it was changed to random distribution. | |**Group Number (GG)**|The middle 2 digits |were originally used for internal group management, but now there are no special rules. | |**Serial Number (SSSS)**|The last 4 digits |serial number (from `0001'to`9999`). | ####**Precautions** -**Invalid numbers**: Some combinations (such as all starting with `0` or `666`) will not be assigned. -**Privacy protection**: SSN is sensitive information, and the public examples are only to illustrate the structure. --- ### **3. Examples of other countries** ####**British National Insurance Number (NINO)** Format: 'AB123456C`, composed of letters and numbers (such as `QQ123456A`), the first two letters must be legally combined. ####**Canadian Social Insurance Number (SIN)** Format: `123-456-789` (9 digits), including the check algorithm, the last digit is the check digit. --- ###**Important reminder** -**The use of real numbers is strictly prohibited**: The above examples are fictitious, and the actual use needs to be generated through official channels. -**Privacy protection**: Social Security numbers are sensitive personal information, so do not disclose or abuse them. If you need more specific regional rules or verification algorithm details, please explain further!