Rounding Decimals

Learning Outcomes

  • Round decimals

There is a squash on a older scale and the scale shows a weight of about 2 pounds.

We can measure many quantities, such as length and weight, to various degrees of accuracy. For example, a chef is preparing a recipe that calls for 1 pound of squash. In the figure to the right, we can see the weight of the squash, to the nearest pound, is 2 pounds. In this case, the chef might decide to use just half of the squash.

Now we will consider a systematic method for rounding decimals.

Round a decimal

  1. Locate the given place value and mark it with an arrow.
  2. Underline the digit to the right of the given place value.
  3. Is this digit greater than or equal to [latex]5?[/latex]
    • Yes – add [latex]1[/latex] to the digit in the given place value
    • No – do not change the digit in the given place value
  4. Rewrite the number, removing all digits to the right of the given place value.

example

Round 18.6372 to the nearest tenth.

example

Round 18.6372 to the nearest hundredth.

Watch the following video to see an example of how to round a number to several different place values.

try it