Ok, I'll bite. The greatest minds in math have differed over this since the abacus was invented. I'm in the "Zero IS considered a number" camp, but it's neither positive nor negative. But it does signify an empty quality, it is used in calculations, it represents a baseline. The same argument has been made that negative numbers are not 'numbers' because they don't represent a quantity. It won't be long before this debate moves over to the Omni forum. So get this back on track, my AA number has a ZERO at the end of it. I never once considered it a letter, but maybe because my account "number" is XXX####.