ZIP codes of Japan are represented by 7 digits numbers using the format 〒NNN-NNNN, where 〒 is the Japanese postal code mark and N is a digit. The first two digits are generally unique to each prefecture: Tokyo has numbers starting with 10-20, Osaka has numbers starting with 53-59. For example, the postcode for the address of Imperial Palace: '1-1 Chiyoda, Chiyoda-ku, Tokyo' is 〒100-0001, and the postcode for the address of Osaka Castle: '1-1 Osaka Castle, Chuo-ku, Osaka City, Osaka Prefecture' is 〒540-0002.