(mathematics) A line that graphically represents the real numbers as a series of points whose distance from an origin is proportional to their value

(mathematics) The minimum, taken over all planar representations of a link or graph, of the number of times it crosses itself.

(arithmetic) A set of numerals for representing numbers.

A measure of the antiknock properties of an automobile fuel; isooctane having an octane number of 100, a fuel with the same antiknock properties as a mixture of 90% isooctane and 10% heptane having an octane number of 90.

(physics) The ratio of the velocity of a body to that of sound in the surrounding medium.

(mathematics) any irrational number that is not an algebraic number

(set theory) Any cardinal or ordinal number which is larger than any finite, i.e. natural number; often represented by the Hebrew letter aleph (ℵ) with a subscript 0, 1, etc.

(computing) A number represented by the binary digits 0 and 1.

(number theory) Any natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers.

(mathematics) The smallest set containing all limits of convergent sequences of rational numbers.