Sweden
In Sweden a Personal Identity Number (Swedish: personnummer) is used in dealings with public agencies, from health care to the tax authorities. It is also commonly used as a customer number in banks and insurance companies. It is written on all approved identity documents, making the risk of mixing up people low. The number uses ten digits, YYMMDD-NNGC. The first six give the birth date in YYMMDD format. Digits seven to nine (NNG) are used to make the number unique, where digit nine (G) is odd for men and even for women. The seventh and eighth digit (for numbers issued before 1990) identify the county of birth or foreign born people. Privacy related criticism caused this system to be abandoned for new numbers.
Read more about this topic: National Identification Number