(complex analysis, strict sense) A number of the form bi, where b is any real number and i denotes the imaginary unit.

(mathematics) An integer / (mathematics) A natural number (positive or non-negative integer)

(mathematics) Of or relating to number theory.

The sequence of digits used to identify a particular destination telephone in a network. / (in the plural, humorous) A large number.

(colloquial) A telephone number.

(mathematics) The branch of pure mathematics concerned with the properties of integers.

plural of tone number

A number allocated to a syllable in various transliteration systems such as Hanyu Pinyin indicating the tone in which it is pronounced.

A telephone number dialled by mistake, for example by transposing digits. / A telephone call received from an unfamiliar caller, due to a mistake in the number dialled.

(idiomatic) A numbers game: the use of inappropriate statistics (numbers) to reflect a desired result (usually misleading). / plural of number game: lotteries, numbers games.