• Key Stage 2 • Maths
Rounding makes a number simpler while keeping it close to its real value. Pupils round to the nearest 10, 100 and 1000 in Year 4 and to any degree of accuracy by Year 6. This guide explains the rules for rounding whole numbers and decimals, with examples and practice questions.
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The Quick Answer
- To round a number, look at the digit to the right of the place you are rounding to.
- If that digit is 5 or more, round up. If it is 4 or less, round down.
- For example, 3,742 rounded to the nearest 100 is 3,700, because the tens digit is 4.
- Pupils use rounding to estimate and check answers to calculations.
When Pupils Learn Rounding
| Year | What the national curriculum says |
|---|---|
| Year 4 | Round any number to the nearest 10, 100 or 1000. Round decimals with one decimal place to the nearest whole number |
| Year 5 | Round any number up to 1,000,000 to the nearest 10, 100, 1000, 10,000 and 100,000. Round decimals with two decimal places to the nearest whole number and to one decimal place |
| Year 6 | Round any whole number to a required degree of accuracy |
How to Round a Number
- Find the digit in the place you are rounding to.
- Look at the digit to its right.
- If it is 5, 6, 7, 8 or 9, add 1 to the rounding digit. If it is 0, 1, 2, 3 or 4, leave the rounding digit as it is.
- Change all the digits after the rounding digit to zeros. For decimals, remove them.
Rounding Whole Numbers
| Number | Round to the nearest | Answer |
|---|---|---|
| 3,742 | 10 | 3,740 |
| 3,742 | 100 | 3,700 |
| 3,742 | 1000 | 4,000 |
| 285,617 | 10,000 | 290,000 |
| 285,617 | 100,000 | 300,000 |
| 4,965 | 100 | 5,000 |
The last example needs care. The hundreds digit is 9 and the tens digit is 6, so the 9 rounds up to 10. That carries into the thousands, giving 5,000.
Rounding Decimals
| Number | Round to | Answer |
|---|---|---|
| 4.6 | The nearest whole number | 5 |
| 12.48 | The nearest whole number | 12 |
| 7.35 | One decimal place | 7.4 |
| 19.96 | One decimal place | 20.0 |
Tip: a number line helps pupils see which value a number is closer to. 3,742 sits between 3,700 and 3,800 and is closer to 3,700.
Using Rounding to Estimate
Rounding is useful for checking whether an answer is sensible. For 398 + 512, round to 400 + 500 = 900. If a calculation gives an answer far from 900, it is worth checking again. The Year 5 curriculum asks pupils to use rounding to check answers to calculations.
Rounding Practice Questions
- Round 467 to the nearest 10.
- Round 2,349 to the nearest 100.
- Round 8,503 to the nearest 1000.
- Round 45,250 to the nearest 1000.
- Round 734,981 to the nearest 10,000.
- Round 650,000 to the nearest 100,000.
- Round 3.7 to the nearest whole number.
- Round 6.25 to one decimal place.
- Round 19.96 to one decimal place.
- Round 2,356,812 to the nearest million.
- Estimate 398 + 512 by rounding each number to the nearest 100.
- A whole number rounded to the nearest 10 is 80. What are the smallest and largest numbers it could be?
Show the answers
- 470
- 2,300
- 9,000
- 45,000
- 730,000
- 700,000
- 4
- 6.3
- 20.0
- 2,000,000
- 400 + 500 = 900
- Smallest 75, largest 84
Common Mistakes
- Looking at the wrong digit: to round to the nearest 100, look at the tens digit, not the ones.
- Rounding 5 down: a 5 always rounds up.
- Forgetting to change the other digits: 3,742 to the nearest 100 is 3,700, not 3,742 or 37.
- Carrying through 9s: 4,965 to the nearest 100 is 5,000, not 4,1000.
Frequently Asked Questions
What is the rule for rounding?
Look at the digit to the right of the place you are rounding to. If it is 5 or more, round up. If it is 4 or less, round down.
Does 5 round up or down?
Up. For example, 45 rounded to the nearest 10 is 50.
What year do children learn rounding?
Pupils round to the nearest 10, 100 and 1000 in Year 4. By Year 6 they round any whole number to a required degree of accuracy.
Why is rounding useful?
It helps you estimate answers and check that a calculation is sensible.
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Sources: Department for Education, National curriculum in England: mathematics programmes of study. Practice questions written by Monster Learning.
