Warm Up

A. Rounding

When performing calculations, especially when division is involved, you may end up with decimal values. To make these decimal values easier to work with, they can be rounded by replacing the number with an approximation that involves fewer decimal places. There are various methods for rounding and three common methods are described below.

Rounding

Replacing one value with another, simpler value that is approximately equal to the original.

 

Rounding to an Increment

"Round to the nearest integer" and "round to the nearest tenth" are both examples of rounding to an increment. To do this, find the digit of interest and look to the digit on its right. If that value is less than 5, keep the digit of interest the same. If the value to the right is greater than or equal to 5, add one to the digit of interest. In either situation, remove any values to the right of the digit of interest.

 

Example 1

  1. Round 4.37 to the nearest whole number.

    Find the whole digit 4.37
    Check the digit to the right 4.37
    The digit to the right is less than 5, so don't change the whole digit. Remove any digits after the whole digit. 4


  2. Round 12.357 to the nearest tenth.

    Find the tenths digit 12.357
    Check the digit to the right 12.35 7
    The digit to the right is 5, so add 1 to the tenths digit. Remove any digits after the tenths digit. 12.4


  3. Round 105.799 to the nearest hundredth.

    Find the hundredths digit 105.79 9
    Check the digit to the right 105.799
    The digit to the right is greater than 5, so add 1 to the hundredths digit. The result is 10 hundredths, which is equivalent to 1 tenth and as such, the tenths digit is increased by 1 and the hundredths digit is 0. Remove any digits after the hundredths digit. 105.80