Compare & order decimals
Theory
To compare decimals, line up the decimal points and compare digits place by place from the left. The first place where the digits differ decides. \(0.9\) is bigger than \(0.86\) because \(9\) tenths beats \(8\) tenths, even though \(0.86\) has more digits. This Year 5 maths page shows how to compare, order and place decimals on a number line.
Line up the decimal points so that each place sits under the same place. Compare the ones, then the tenths, then the hundredths, then the thousandths.
Zeros on the end of a decimal do not change its value: \(0.36 = 0.360\). Adding them can make decimals easier to compare.
More digits does not mean bigger. \(0.375\) is less than \(0.4\) because it has only \(3\) tenths.
Ascending order means smallest to largest; descending order means largest to smallest. \(>\) means is greater than and \(<\) means is less than.
Compare place by place from the left:
How to compare two decimals
- Line up the decimal points.
- Add zeros on the end so both have the same number of decimal places.
- Compare from the left until two digits are different.
- The bigger digit belongs to the bigger number.
How to order several decimals
- Write them all with the same number of decimal places.
- Order them, then write them as they were given.
| \(0.30\) | \(>\) | \(0.29\) |
\(0.3\), because \(3\) tenths is more than \(2\) tenths.
(i) \(5.08\) ___ \(5.8\)
(ii) \(0.71\) ___ \(0.709\)
| \(5.08\) | \(<\) | \(5.80\) |
| \(0.710\) | \(>\) | \(0.709\) |
(i) \(5.08 < 5.8\)
(ii) \(0.71 > 0.709\)
| \(0.36\) | \(=\) | \(0.360\) |
\(0.360\). A zero on the end adds no value.
As thousandths: \(7.205\), \(7.250\), \(7.025\), \(7.520\).
| \(7.025\) | \(<\) | \(7.205 < 7.25 < 7.52\) |
\(7.025,\ 7.205,\ 7.25,\ 7.52\).
(i) Which time is the fastest (smallest)?
(ii) Write the times in descending order.
As thousandths: \(9.840\), \(9.408\), \(9.480\), \(9.800\).
| \(9.84\) | \(>\) | \(9.8 > 9.48 > 9.408\) |
(i) \(9.408\) s
(ii) \(9.84,\ 9.8,\ 9.48,\ 9.408\)
| \(2.60\) | \(<\) | \(2.65 < 2.70\) |
\(2.65\) works (so does any decimal from \(2.61\) to \(2.69\)).
| \(0.6 + 4 \times 0.01\) | \(=\) | \(0.64\) |
\(0.64\).
| \(0.375\) | \(<\) | \(0.400\) |
Compare tenths first: \(3\) tenths is less than \(4\) tenths. So \(0.4\) is larger.
Common pitfalls
Frequently asked questions
How do you compare decimals?
Line up the decimal points and compare from the left. The first place that is different decides: \(0.3 > 0.29\).
Is a decimal with more digits bigger?
Not always. \(0.4\) is bigger than \(0.375\) because it has more tenths.
Do zeros at the end of a decimal matter?
No. \(0.36 = 0.360\). They can help you compare.
How do you find a decimal between two decimals?
Add another decimal place: between \(2.6\) and \(2.7\) are \(2.61, 2.62, \ldots, 2.69\).
What is descending order?
Largest to smallest.