**Estimation** is the process of rounding numbers before performing operations to make operations easier. Estimation can be used when an exact answer is not necessary or to check work.

To **round** a number, first identify the digit in the specified place value. Then look at the digit one place to the right. If that digit is 4 or less, keep the digit in the specified place value the same. If that digit is 5 or more, add 1 to the digit in the specified place value. All the digits to the right of the specified place value become zeros.