Sweden, I assume. The personnummer (personal number) consists of the following:<p>- The birth date, e.g. 640823 (YYMMDD)<p>- The birth number, three digits. Last digit is odd for men and even for women.<p>- A check digit, calculated by the Luhn algorithm.<p>A full example:
640823-3234 -- a male born on August 23, 1964.