Real number

A real number is a number that falls on the real number line. It can have any value. Some examples of real numbers are: $1, 2, -23.25, 0, \frac{\pi}{\phi}$ , and so on. Numbers that are not real are $\ 3i$ , $\ 3+2.5i$ , $\ 3+2i+2j+k$ , i.e. complex numbers, and quaternions.

The set of real numbers, denoted by $\mathbb{R}$ , is a subset of complex numbers( $\mathbb{C}$ ). Commonly used subsets of the real numbers are the rational numbers ( $\mathbb{Q}$ ), integers ( $\displaystyle\mathbb{Z}$ ), natural numbers ( $\mathbb{N}$ ) and irrational numbers (sometimes, but not universally, denoted $\mathbb{J}$ ). In addition $\displaystyle\mathbb{Z}^{+}$ means positive integers and $\displaystyle\mathbb{Z}^{-}$ means negative integers. The real numbers can also be divided between the algebraic numbers and transcendental numbers, although these two classes are best understood as subsets of the complex numbers.

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Real number

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