Rounding to Decimal Places

## Rounding to Decimal Places

Rounding numbers to decimal places involves counting the required number of decimal places after the decimal point; then checking the next decimal place to determine the rounding required. If the next decimal place is 5 or more, the number is rounded up.

For example, giving 0.54603 to two decimal places would be 0.54: but check the following (third) decimal place. It is a 6, so the number is rounded up to 0.55.

Decimal Places are sometimes abbreviated to dp: the number 23.456 which is accurate to three decimal places will be shown as 23.456 (3dp).

Examples of rounding to decimal places:

 Number 0.52064 23.8569 0.000543 1 decimal place 0.5 23.9 0 2 decimal places 0.52 23.86 0 3 decimal places 0.521 23.857 0.001

## Example 1

An experiment in a physics lab has shown that the force required to move an object was 2.466 Newtons. What is this force measured to 1 decimal place (1 dp)?

The number is 2.4 to 1dp; check the following digit (6). As it is greater than 5 then round the number up.

Charlie bought a book for £10. It had frac(1)(3) off because it was in a sale. How much did Charlie pay?
The purchase price is 10 x frac(2)(3) = 6.66666 recurring, or 6.dot6. Round to 2 decimal places (for pence) gives 6.67. The implication to round to 2 decimal places is given by the use of pounds and pence.