Rounding numbers is used when estimating to make numbers easier to work with, especially when just a general amount is needed instead of an exact amount.
To round off a number determine the last digit to be kept. If the number immediately to the right of it is less than five, then it stays the same. If the digit to the right is equal to or greater than five, add one to digit.
Whether a number is rounded up or down, the digits following the cutoff point all become zero. This method can be used for whole numbers and decimals.
Estimating can be useful when working with distances and money amounts.