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81 as well as all whole numbers are rational numbers. Any number that can be written as a fraction is a rational number. An irrational number can be written as a decimal, but not as a fraction.
An irrational number has endless non-repeating digits to the right of the decimal point. An example of an irrational number would be pi:
π = 3.141592…
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Earn +20 ptsQ: Is 81 a rational or irrational number?
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Continue Learning about Algebra
Is the root of 81 an irrational number?
No. The square root of 81 is 9, which is a rational number.
Is 10.01 a rational or irrational number?
10.01 is a rational number
Is 37.5 a rational or irrational number?
Rational
Is the product of a rational number and an irrational number rational or irrational?
Such a product is always irrational - unless the rational number happens to be zero.
The sum of a rational number and an irrational number is?
The sum of a rational and irrational number must be an irrational number.
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