Rounding calculator: nearest whole number, ten, hundred or decimal place

The rounding rule

• Find the place you're rounding to, and look at the digit in that place.
• Look at the digit just to its right.
• If it's 5 or more, round up: add 1 to your digit.
• If it's 4 or less, round down: your digit stays the same.
• Change every digit after your place to 0, or drop it if it's after the decimal point.

Worked example: round 3,486.274

To the nearest hundred, look at the hundreds digit, 4. The next digit is 8, which is 5 or more, so round up to 3,500. To the nearest whole number, look at the ones digit, 6. The next digit is 2, so round down to 3,486. To the nearest tenth, the tenths digit is 2 and the next is 7, so round up to 3,486.3.

Rounding up past a 9

When the digit you're rounding up is a 9, it becomes 0 and you carry 1 to the left, just like adding. 3,960 to the nearest hundred: the hundreds digit is 9, the next digit is 6, so the 9 becomes 10, giving 4,000. And 2.97 to the nearest tenth is 3.0, not 2.10.

Rounding on a number line

Rounding asks which multiple of ten, hundred or tenth a number is closest to. On a number line from 3,400 to 3,500, the number 3,486 sits much nearer 3,500, so that's where it rounds. A number exactly halfway, such as 3,450, is rounded up by the school rule.