Step by step
The question
Question: which is smaller, −1/3 or −0.3?
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: 1 divided by 3, one digit at a time.
10 divided by 3 is 3, with 1 left.
1 left again: the 3 repeats for ever.
So −1/3 is −0.333….
Careful!
−1/3 is not −0.3.
Its 3s go on for ever, so it is a bit further below 0 than −0.3.
2 Same number of digits
Zeros at the end of a decimal do not change it: −0.3 is the same as −0.300.
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.
3 Compare
Negative numbers are below 0.
333 > 300, so −0.333… is further below 0.
Further below 0 means smaller.
4 Write the answer
Now with the numbers as they were given: −1/3 < −0.3.
So −1/3 is smaller.
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: −1/3, −0.3.
The same order.
So the answer is right!
Let's look back.
First: write it as a decimal.
Then: same number of digits.
Then: compare.
Then: write the answer.
Last: check.