Social security numbers (or similar identification systems) in different countries and regions have unique generation rules and structural designs, which are mainly used in public administration such as social security, taxation, and medical care. The following are the rules and examples of social security numbers in several common countries/regions. It should be noted that **All examples are fictitious** and **cannot be used for practical purposes**. --- ### **1. U.S. Social Security Number (SSN)** -**Format**:`AAA-GG-SSSS` -**AAA** (the first three digits): Originally the Area Number, it has been randomly assigned (avoid the range of `000`, `666` and `900-999`). -**GG**(middle two digits): Group Number (Group Number), has no specific geographical significance, and is used for management classification. -**SSSS**(last four digits): Serial Number, randomly generated. -**Example**: `123-45-6789` (fictitious, real SSNs need to avoid using similar common examples). -**Note**: SSN does not contain date of birth information, and the public use of real numbers is prohibited. --- ### **2. Chinese citizenship number (one social security number)** -**Format**: 18 digits, the structure is 'AAAAAA YYYYMMDD SSS C` -**AAAAAA**: The first 6 digits are the administrative division code of the place of residence (for example, `110102' is Xicheng District, Beijing). -**YYYYMMDD**: Date of birth. -**SSS**: Sequence code, odd male, even female. -**C**: Check code (0-9 or X), generated by the ISO 7064 algorithm. -**Example**: `11010219900307213X` (fictitious, the check code may be invalid). -**Verification**: The legitimacy of the verification code can be verified through a public algorithm. --- ### **3. British National Insurance Number (NINO)** -**Format**:'AB123456C` (combination of letters + numbers) -The first two letters (such as 'AB`), followed by 6 digits, and the last letter (such as `C`). -Exclude specific prefixes (such as `BG`,`NK' and other confusing combinations). -**Example**: `AB123456C` (fictitious, real NINO needs to be allocated through government agencies). -**Purpose**: Used in tax, social security and pension systems. --- ### **4. French INSEE code (social Security number)** -**Format**: 15 digits, including gender and birth information. -**Structure**: `1 YY MM DDD SSS CC` -`1`: gender (1 male, 2 female). -`YYMM`: Two digits and month after the year of birth. -'DDD`: The administrative district code of the place of birth. -'SSSS`: Sequence number. -'CC`: Check code. -**Example**：`1 90 03 751 123 12`（ Fiction). --- ###**Important Notes** 1. **Legal purpose**: Social security numbers are sensitive personal information, and unauthorized generation or use of real numbers is prohibited. 2. **Privacy protection**: Disclosing or disclosing other people's Social Security numbers may violate laws (such as the European Union's General Data Protection Regulation and the U.S. Privacy Act). 3. **Test data**: Obviously fictitious numbers (such as examples starting with `000` or `999`) need to be used in development or testing. For more information about the rules of a particular country, it is recommended to consult official government documents or legal guidelines.