Rounding to decimal places
You learn to round a decimal to a whole number or to a number of decimal places.
How to work it out
- Count how many digits after the decimal point you are allowed to keep.
- Look at the digit that comes next.
- If it is 5 or more, your last digit goes up one.
- If it is less, it stays the same.
A worked example
Round 3.14 to 1 decimal place
- You keep 1 digit after the decimal point.
- Look at the next digit: the 4.
- That is less than 5, so round down: 3.1.
More examples
Round 16.5 to the nearest whole number
- You keep no digits after the decimal point.
- Look at the first digit after it: the 5.
- That is 5 or more, so round up: 17.
Round 4.568 to 2 decimal places
- You keep 2 digits after the decimal point.
- Look at the next digit: the 8.
- That is 5 or more, so round up: 4.57.
Try it yourself
Round 7.995 to 2 decimal places
Round 16.5 to the nearest whole number
Watch out
You just cut the digits off, even if the next digit is 5 or more: 16.5 becomes 16.
Always look at the first digit you drop. If it is 5 or more, the last digit you keep goes up.
You round 9.96 to 1 decimal place and write 9.10.
One more tenth on 9.9 makes 10.0, and you write that as 10.
Tips
- Only the first digit you drop counts; the digits after it do not matter.
- If a 9 goes up, the digit in front of it changes too.
Why it works
Rounding decimals works just like rounding whole numbers. You look at the first digit you drop. If it is 5 or more, the last digit you keep goes up by one.