the number applies to the length of the hair when they are done cutting, and the type of plastic attachment they add to their clippers. 0 is the shortest you can get, and the higher the numbers go the longer the hair is when they're done cutting (I believe you can go up to 8). Why would you get pissed off at this? It just makes it easier on the barber to know which setting to use rather than having a non-descriptive "I want it short" or "I want a man's haircut". Who defines what a man's haircut is? How the hell is the barber supposed to know what your definition of "short" is?