(slang) A fan of the English synthpop musician Gary Numan (born 1958).

(mathematics) A non-negative integer, the representation of whose square in its base can be split into two parts that add up to itself (such as 297, whose square, 88209, can be split into 88 and 209, totalling 297).

(somewhat rare) A number theorist.

plural of number theoretician

(fluid mechanics) A dimensionless number defined as the ratio of a characteristic velocity to a gravitational wave velocity, used in fluid mechanics to determine the resistance of an object moving through water.

plural of number plate

A measure of fineness of a mesh: the numerical value indicates the number of openings per linear inch. The smaller the mesh number, the larger particles can pass through the mesh.

(physics) The number of electrons in an atom or ion

(mathematics) The complete Archimedean ordered field (of real numbers).

(mathematics) The real number system adjoined with two extra symbols: ∞ and −∞, inheriting the ordering of the real number system, and defining −∞ to be less than any real number, and ∞ to be larger than any real number.