(mathematics) Any of the large semiprime numbers to be factored in the RSA Factoring Challenge, a competition from 1991 to 2007 encouraging research into computational number theory.

(law) a number that represents information which is illegal to possess, utter or propagate. Any information that can be represented in binary format is, ipso facto, representable as a number, and therefore if the information itself is illegal in some way, the pure number itself may be called illegal.

An ordinal number that distinguishes a monarch from others of the same name.

(logic) A number uniquely assigned to each symbol, and to each well-formed formula of some formal language.

(number theory) Any number of the form k·2ⁿ + 1, where k is odd, n is a positive integer, and 2ⁿ > k.

(mathematics) Any of a set of numbers which extends the set of real numbers by including infinitesimals and infinities, and is used in nonstandard analysis.

For a given set of coprime positive integers, the greatest integer that cannot be expressed as a linear combination (with nonnegative integer coefficients) of its elements.

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.

plural of number plate

(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).