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Compare 2/3 and 0.6

Step by step, with the reason for every step · Ordering mixed numbers and repeating decimals · Foundations

Step by step

The question

Question: compare 2/3 and 0.6.

23 and 0.6

1 Write it as a decimal

To compare, we write every number the same way: as a decimal.

The bottom 3 does not go into 10, 100 or 1000.

So we divide: 2 divided by 3, one digit at a time.

= 23 = 2 ÷ 3 = 0.666…

20 divided by 3 is 6, with 2 left.

2 left again: the 6 repeats for ever.

So 2/3 is 0.666….

20 ÷ 3 = 6, 2 left: the 6 repeats

Careful!

2/3 is not 0.6.

Its 6s go on for ever, so it is a bit more than 0.6.

Careful: not 23 = 0.6 ✗

2 Same number of digits

Zeros at the end of a decimal do not change it: 0.6 is the same as 0.600.

A repeating decimal goes on for ever, so we can write as many of its digits as we need.

So we give every number 3 digits after the point.

= 0.666…, 0.600

3 Compare

Now both have 3 digits after the point.

So we can forget the point and compare them like whole numbers: 600 < 666.

= 0.600 < 0.666…
600 < 666

4 Write the answer

Now with the numbers as they were given: 2/3 > 0.6.

2/3 is greater than 0.6.

= 23 > 0.6

5 Check

Let's check on a number line.

Smaller numbers are further to the left.

We put a dot for each number.

From left to right: 0.6, 2/3.

The same order.

So the answer is right!

left to right: same order

Let's look back.

First: write it as a decimal.

Then: same number of digits.

Then: compare.

Then: write the answer.

Last: check.

Answer
= 23 > 0.6

Your turn

Try this one yourself, then check:

13 and 0.3
Show the answer
13 > 0.3

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