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Is 0.5 rational or irrational

Step by step, with the reason for every step · Rational or irrational · Foundations

Step by step

The question

Question: is 0.5 rational or irrational?

0.5

Rational means: it can be written as a fraction, with whole numbers on top and at the bottom.

Then its decimal stops, or repeats for ever.

Irrational means: no fraction works.

Its decimal never stops and never repeats.

rational = a fraction of whole numbers
decimal stops or repeats

1 Write it as a fraction

The last digit is in the tenths.

So we write it over 10.

tenths: over 10

0.5 is 5/10.

That makes simpler: 1/2.

= 510 = 12

So 0.5 is rational.

Its decimal stops, and it is a fraction of whole numbers.

= 0.5 is rational

2 Check

Let's check: 1 divided by 2 is 0.5.

We get the decimal back.

So the answer is right!

1 ÷ 2 = 0.5

Let's look back.

First: write it as a fraction.

Last: check.

Answer
= 0.5 is rational

Your turn

Try this one yourself, then check:

Is 0.1
Show the answer
rational

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