# Difference between revisions of "Real number"

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

− | The set of real numbers is denoted by <math>\mathbb{R}</math>. Commonly used subsets of the real numbers are irrational numbers, rational numbers, integers, and natural numbers. | + | The set of real numbers is denoted by <math>\mathbb{R}</math>. Commonly used subsets of the real numbers are irrational numbers (<math>\mathbb{J}</math>), rational numbers (<math>\mathbb{Q}</math>), integers (<math>\displaystyle\mathbb{Z}</math>), and natural numbers (<math>\mathbb{N}</math>). |

## Revision as of 17:31, 24 June 2006

A **real number** is a number that falls on the real number line. It can have any value. Some examples of real numbers are:, and so on. Numbers that are not real are , , , i.e. complex numbers, and quaternions.

The set of real numbers is denoted by . Commonly used subsets of the real numbers are irrational numbers (), rational numbers (), integers (), and natural numbers ().