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Irrational number

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An irrational number is a real number that cannot be expressed as the ratio of two integers. Equivalently, an irrational number, when expressed in decimal notation, never terminates nor repeats. Examples are \pi, \sqrt{2}, e, \sqrt{32134}, etc.

Because the rational numbers are countable while the reals are uncountable, one can say that the irrational numbers make up "almost all" of the real numbers.


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