Real number

A real number is either a rational number or an irrational number. The set of real numbers is denoted by [math]\displaystyle{ \mathbb{R} }[/math].

Formally, [math]\displaystyle{ \mathbb{R} }[/math] can be constructed from [math]\displaystyle{ \mathbb{Q} }[/math], the set of rational numbers using Dedekind cuts.

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• Real number

Number classes

General numbers

Integer Natural Even Odd Rational Irrational Real Prime Probable prime

Special numbers

Mersenne 2n-1 Fermat 22n+1 Proth k•2n+1 Riesel k•2n-1 Woodall n•2n-1 Cullen n•2n+1 Double Mersenne 22p-1-1 Perfect 2n-1(2n-1) Leyland xy ± yx Gen.Repunit (b^n-1)/(b-1)

Prime numbers

Mersenne Proth Riesel Williams (b±1)bn±1 Carol/Kynea (bn±1)2-2 Multifactorial n!j±1