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Write 0.222... as a fraction

Step by step, with the reason for every step · Repeating decimals to fractions · Foundations

Step by step

The question

Question: write 0.222 repeating as a fraction.

0.222…

Look at the digits.

The 2 repeats for ever.

2 repeats for ever

1 Call it x

We do not know the fraction yet.

So we call the number x: x = 0.222 repeating.

x = 0.222…

Careful!

It is not 2/10.

That is 0.2, which stops.

Ours goes on for ever.

Careful: not 0.222… = 210 ✗

2 Move the point

1 digit repeats.

So we multiply both sides by 10.

That moves the point 1 place to the right.

10x = 2.222…
× 10: point moves 1 place

3 Take away

Now we take the first one away from the new one.

Both sides, so they stay equal.

10x − x = 2.222… − 0.222…

After the point, both go on with 2 for ever.

The tails are exactly the same, so they make zero.

Cross them out.

10x minus x is 9x.

2 minus 0 is 2.

9x = 2

4 Remove the 9

9x means 9 times x.

We want just x.

To remove times 9, we divide by 9.

9x9 = 29

9 divided by 9 is 1.

So just x is left.

So x = 2/9.

x = 29

So 0.222 repeating is 2/9.

5 Check

Let's check: 2 divided by 9.

We get 0.222, and the digits go on the same way.

That is 0.222 repeating.

So the answer is right!

2 ÷ 9 = 0.222…

Let's look back.

First: call it x.

Then: move the point.

Then: take away.

Then: remove the 9.

Last: check.

Answer
x = 29

Your turn

Try this one yourself, then check:

Write 0.888…
Show the answer
89

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