A hundred street address numbers were provided for every block to the east or west of Fifth Avenue; for instance, the addresses on West 50th Street between Fifth and Sixth Avenues were numbered 1–99 West 50th Street, and between Sixth and Seventh Avenues 100–199 West 50th Street.[27] The building lot numbering system worked similarly on the East Side before Madison and Lexington Avenues were added to the street grid laid out in the Commissioners' Plan of 1811. Unlike at other avenues, west-east street addresses do not increment to the next hundred to the east of Madison and Lexington Avenues.