It shall be the duty of each resident owner of a building in the city and of the occupant of each building therein owned by nonresidents to procure the proper numbers for such building and affix the same in a conspicuous place to the front of such building. It shall be the duty of any person hereafter erecting any building in the city, within ten days after the issuance of a certificate of occupancy, to procure the proper numbers and affix the same to such new building.