There are two sets of street numbers, red and black (or blue). Generally, all the red numbers are for business and merchants. Black numbers are for residences. Walking down a street in Florence you may see an 80 black next to a 132 red. So be sure to pay attention to which colour you are looking for. You will often see an address for a store listed as 11 r, which means that the number 11 is painted in red, or rosso.