Zero is really a concept summed by a symbol, not truly a number(I know Webster says otherwise, but that is an incredibly vague definition). A little support: anything divided by zero is not a value, but anything divided by a number is. Zero is also not odd or even (many say even just because of where it sits on a number line) Ancient civilizations had all the tradition numbers(a complete set of number), granted symbolized differently, and it took 100s of years for a zero to show up because it is an abstract thing. Nothing is not a quantity, it is a highly abstract idea.