Every taxicab licensed to operate in the City shall be assigned a number by the licensee approved by the City Treasurer and filed with the City Clerk, and it shall be unlawful to operate a taxicab within the City unless such number is painted on each rear side door of the taxicab; the numerals used shall be plain and legible block numerals at least two inches in height and one inch between numerals. (Code 1981 § 46-40. Code 1995 § 154-67.)