'''Number''' is an abstraction of the concept of quantity. The earliest number systems consisted solely of [[natural numbers]]; however, as needs arose, these were expanded to more complex concepts, such as [[decimals]].
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A '''number''' is a term that describes the amount of something and is used for counting of measuring.
Numbers are usually represented in [[English]] writing by a system of ''numerals'':
Numbers are usually represented in [[English]] writing by a system of ''numerals'':
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*9 (nine)
*9 (nine)
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which can be used in combination to approximate any real number to arbitrary precision. An older system of representation, still sometime encountered on clocks and other places, is [[Roman numeral]]s, which used certain letters of the [[alphabet]] instead.
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Which can be used in combination to represent any number of any size. An older system of representation, still sometime encountered on clocks and other places, is [[Roman numeral]]s, which used certain letters of the [[alphabet]] instead.
There are many kinds of numbers. Some examples are:
There are many kinds of numbers. Some examples are:
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*[[Complex number]]s
*[[Complex number]]s
*[[Transcendental number]]s
*[[Transcendental number]]s
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It should be noted that number systems further removed from the natural numbers frequently have counter-intuitive properties. For instance, the complex numbers are ''not'' an [[ordered field]], and cannot be represented on a single line. Other even more abstruse constructions are the [[quaternions]] and the [[octonions]]; whilst these are both sometimes called number systems, whether these deserve to be called so is another matter. Essentially, the concept of number is not amenable to definition.