Estimating Rational Numbers' Sums and Differences:

Remember to round to the nearest whole number (or integer) when working with estimates of rational numbers UNLESS the numbers are between -1 and 1. Then, estimate to nearest -1, -1/2, 0, 1/2, or 1. It is worth the effort to form an estimate when working with rational number operations so that the answer can be checked for reasonableness.