How to write 甲甲

first of the ten Heavenly Stems 干; (used for an unspecified person or thing); first (in a list, as a party to a contract etc); letter "A" or roman "I" in list "A, B, C", or "I, II, III" etc; armor plating; shell or carapace; (of the fingers or toes) nail; bladed leather or metal armor (old); ranking system used in the Imperial examinations (old); civil administration unit in the baojia 甲 system (old); ancient Chinese compass point: 75°