# irrational number

## irrational number

noun Mathematics.
a number that cannot be exactly expressed as a ratio of two integers.

Origin:
1545–55

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Based on the Random House Dictionary, © Random House, Inc. 2014.
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Collins
World English Dictionary
 irrational number —n any real number that cannot be expressed as the ratio of two integers, such as π

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Science Dictionary
 irrational number   (ĭ-rāsh'ə-nəl)  Pronunciation Key  A number that cannot be expressed as a ratio between two integers and is not an imaginary number. If written in decimal notation, an irrational number would have an infinite number of digits to the right of the decimal point, without repetition. Pi and the square root of 2 (√2) are irrational numbers.
The American Heritage® Science Dictionary
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American Heritage
Cultural Dictionary

### irrational number definition

A number that cannot be expressed as the ratio of two whole numbers.

Note: The square roots of most whole numbers are irrational numbers.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
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FOLDOC
Computing Dictionary

### irrational number definition

mathematics
A real number which is not a rational number, i.e. it is not the ratio of two integers.
The decimal expansion of an irrational is infinite but does not end in an infinite repeating sequence of digits.
Examples of irrational numbers are pi, e and the square root of two.
(1995-04-12)

The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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Example sentences
The value pi is an irrational number and never ending.
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