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The most common meaning of the term zero is the absence of any magnitude or quantity. For example, a person might say that he or she has zero children, meaning that he or she has no children. In this respect, zero is a number, like 2, +9, −45, or 0.392. It can be used in mathematical operations in nearly all of the same ways that nonzero numbers can be used. For example, 4 + 0 = 4 is a legitimate mathematical operation. One mathematical operation from which zero is omitted is division. One can divide 0 by any number (in which case the answer is always zero), but one cannot divide any number by zero. That is, the mathematical operation 4 ÷ 0 has no meaning.

Zeroes also have other functions. For example, a zero may indicate the beginning of some counting system. A temperature of zero degrees kelvin (0 K), for example, is the starting point for the absolute temperature...