- AKA: Zero.
- See: Integer, Empty Set, Zero Vector, Zero Matrix, Zero (number), Numerical Digit, Numeral System, Additive Identity.
- (Wikipedia, 2014) ⇒ http://en.wikipedia.org/wiki/0_(number) Retrieved:2014-11-12.
- 0 (zero ; BrE: or AmE: ) is both a number  and the numerical digit used to represent that number in numerals. It fulfills a central role in mathematics as the additive identity of the integers, real numbers, and many other algebraic structures. As a digit, 0 is used as a placeholder in place value systems. In the English language, 0 may be called zero, nought or (US) naught, nil, or — in contexts where at least one adjacent digit distinguishes it from the letter "O" — oh or o. Informal or slang terms for zero include zilch and zip. Ought or aught () has also been used historically.