Portal:Numbers

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Introduction

A number is a mathematical object used to count, measure, and also label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. A notational symbol that represents a number is called a numeral. In addition to their use in counting and measuring, numerals are often used for labels (as with telephone numbers), for ordering (as with serial numbers), and for codes (as with ISBNs). In common usage, number may refer to a symbol, a word, or a mathematical abstraction.

In mathematics, the notion of number has been extended over the centuries to include 0, negative numbers, rational numbers such as 1/2 and 2/3, real numbers such as 2 and π, and complex numbers, which extend the real numbers by adding a square root of −1. Calculations with numbers are done with arithmetical operations, the most familiar being addition, subtraction, multiplication, division, and exponentiation. Their study or usage is called arithmetic. The same term may also refer to number theory, the study of the properties of numbers.

Selected general articles

Did you know...

Need help?

Do you have a question about Numbers that you can't find the answer to?

Consider asking it at the Wikipedia reference desk.

Get involved

For editor resources and to collaborate with other editors on improving Wikipedia's Numbers-related articles, see WikiProject Numbers.

Selected images

Subcategories

Topics

Associated Wikimedia

The following Wikimedia Foundation sister projects provide more on this subject:

Wikibooks
Books

Commons
Media

Wikinews 
News

Wikiquote 
Quotations

Wikisource 
Texts

Wikiversity
Learning resources

Wiktionary 
Definitions

Wikidata 
Database

Purge server cache