(chemistry) The hypothetical charge of an atom within a molecule.

(cricket) The batsman who bats last; usually the worst batsman in the side.

A back issue of a magazine, etc. / Anything considered old-fashioned.

A number whose decimal representation ends in one or more zeroes. / A rough approximation, especially one whose decimal representation ends in one or more zeroes.

A unique number, assigned to a particular unit of some product, to identify it.

(computing) The character # used to represent the word number; the hash sign; also called the pound sign in the US

A common alternative form of PIN (in the sense of "personal identification number").

(mathematics) The set of numbers that can be expressed as a ratio of integers, often denoted with the bold letter Q, or the blackboard bold letter ℚ.

(mathematics) A number that can be expressed as the ratio of two integers.

(mathematics) The set of positive integers, {1, 2, 3, ...}. / (mathematics, computer science) The set of non-negative integers, {0, 1, 2, 3, ...}.