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Numbers can be classified according to how they are represented or according to the properties that they have. ==Main types== Natural numbers (): The counting numbers , are called natural numbers. Some authors include 0, so that the natural numbers are . Whole numbers: The numbers . Integers (): Positive and negative counting numbers, as well as zero:. Rational numbers (): Numbers that can be expressed as a ratio of an integer to a non-zero integer.〔()〕 All integers are rational, but the converse is not true. Real numbers (): Numbers that have decimal representations that have a finite or infinite sequence of digits to the right of the decimal point. All rational numbers are real, but the converse is not true. Irrational numbers (): Real numbers that are not rational. Imaginary numbers: Numbers that equal the product of a real number and the square root of –1. The number 0 is both real and imaginary. Complex numbers (): Includes real numbers, imaginary numbers, and sums and differences of real and imaginary numbers. Hypercomplex numbers include various number-system extensions: quaternions (), octonions (), sedenions (), tessarines, coquaternions, and biquaternions. p-adic numbers: Various number systems constructed using limits of rational numbers, according to notions of "limit" different from the one used to construct the real numbers. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「List of types of numbers」の詳細全文を読む スポンサード リンク
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