The rules for generating social security card numbers (that is, social security numbers) vary from country to country or region. The following takes the Chinese Social Security Card as an example to illustrate its generation logic and provide examples, but it should be noted that **The actual number cannot be leaked or forged**, here is only a description of the rules： --- ###**China Social Security Card Number Rules (18 digits)** China's social security card number is usually the same as the citizen ID number (18 digits) and consists of the following parts： 1. **Address code (digits 1-6)**: The administrative division code of the place where the registered account is located (for example, Chaoyang District, Beijing is `110105`). 2. **Date of birth code (7th-14th digits)**: Date of birth (for example, `19900101'represents January 1, 1990). 3. **Sequence code (digits 15-17)**: The sequence number of those born on the same birthday in the same region, odd-numbered men and even-numbered women. 4. **Check code (18th digit)**: Calculated from the first 17 digits (ISO 7064:1983 standard). **Example (fictitious number)**： `110105199001011234` -`110105': Chaoyang District, Beijing -`19900101`: Born on January 1, 1990 -`123`: The 123rd (male) born on the same day -`4`: check code --- ###**Examples of social Security numbers in other countries/regions** 1. **United States (SSN, 9 digits)** -Format: 'AAA-GG-SSSS` -Example: `123-45-6789' (the first 3 digits are the area code, the middle 2 digits are the group number, and the last 4 digits are the sequence number). - *Note: The SSN has now been randomly generated and no longer reflects the geographic location. * 2. **United Kingdom (NINO, 9 digits)** -Format: 'AB 12 34 56 C` -Example: `AB 12 34 56 A` (the first 2 letters are the type, the middle 6 digits are the serial number, and the last letter is the checksum). --- ###**Precautions** -**Privacy protection**: The Social Security number is sensitive information, so do not disclose or change the real number. -**Regional differences**: For specific rules, please refer to local social security agencies (for example, there may be individual adjustments in various parts of China). -**Purpose**: The social security number is used for medical care, pension and other benefits, and is bound to personal taxation and credit. For more information, it is recommended to consult the local social security department or visit the official website (such as China`12333.gov.cn `).