The number of people, statistically, who must be exposed to something in order for one of them to experience an adverse effect.

(mathematics) A geometric representation of the real number system.

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

plural of purely imaginary number

plural of private enterprise number

(India, politics) A number assigned to each of the adult citizens and residents of India in order to identify them officially.

(physics) A quantum number of an atomic orbital, whose possible values are related to the azimuthal quantum number, that denotes the energy levels in a subshell.

(physics) A quantum number that specifies the spin of a particle; for an electron, it may only take the values ±1/2

(physics) The quantum number (of an atomic orbital) that specifies the energy of an electron in an atom and, hence, which shell it occupies

(telecommunications) A number denoting the electrical load of a telephone ringer circuit on a particular line.