Rational or irrational, step by step
One question decides it: can the number be written as a fraction of two whole numbers?
The question
Rational or irrational?
0.1
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a decimal that stops can be written over a power of ten
0.1isrational
- One question decides it: can this be written as a fraction of two whole numbers? Not "does it look tidy", and not "is there a root sign" — those are the two guesses that go wrong.
- Look at what kind of number it is: a decimal that stops can be written over a power of ten.
- So it CAN be written as a fraction. That makes it rational.
How it works.
- 01
One question decides it: can this be written as a fraction of two whole numbers? Not "does it look tidy", and not "is there a root sign" — those are the two guesses that go wrong.
- 02
Look at what kind of number it is: a decimal that stops can be written over a power of ten.
- 03
So it CAN be written as a fraction. That makes it rational.