Personal identification number (Denmark)

The Danish Personal Identification number (personnummer or informally Danish: CPR-nummer, Greenlandic: CPR-normu or inuup-normua) is a national identification number, which is part of the personal information stored in the Civil Registration System (Danish: Det Centrale Personregister, Greenlandic: Inunnik Qitiusumik Nalunaarsuiffik).

The register was established in 1968 by combining information from all the municipal civil registers of Denmark into one.^[1] The register came into force by royal assent in Greenland with the effect from 1 July 1972.^[2]

It is a ten-digit number with the format DDMMYY-SSSS, where DDMMYY is the date of birth and SSSS is a sequence number. The first digit of the sequence number encodes the century of birth (so that centenarians are distinguished from infants), and the last digit of the sequence number is odd for males and even for females.^[3]