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Write 0.070707... as a fraction

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

Step by step

The question

Question: write 0.0707 repeating as a fraction.

0.0707…

Look at the digits.

The block 0 7 repeats for ever.

07 repeats for ever

1 Call it x

We do not know the fraction yet.

So we call the number x: x = 0.0707 repeating.

x = 0.0707…

Careful!

It is not 7/100.

That is 0.07, which stops.

Ours goes on for ever.

Careful: not 0.0707… = 7100 ✗

2 Move the point

2 digits repeat.

So we multiply both sides by 100.

That moves the point 2 places to the right, one whole block.

100x = 7.0707…
× 100: point moves 2 places

3 Take away

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

Both sides, so they stay equal.

100x − x = 7.0707… − 0.0707…

After the point, both go on with 0 7 for ever.

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

Cross them out.

100x minus x is 99x.

7 minus 0 is 7.

99x = 7

4 Remove the 99

99x means 99 times x.

We want just x.

To remove times 99, we divide by 99.

99x99 = 799

99 divided by 99 is 1.

So just x is left.

So x = 7/99.

x = 799

So 0.0707 repeating is 7/99.

5 Check

Let's check: 7 divided by 99.

We get 0.0707, and the digits go on the same way.

That is 0.0707 repeating.

So the answer is right!

7 ÷ 99 = 0.0707…

Let's look back.

First: call it x.

Then: move the point.

Then: take away.

Then: remove the 99.

Last: check.

Answer
x = 799

Your turn

Try this one yourself, then check:

Write 0.9898…
Show the answer
9899

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