How to Estimate the Sums and Differences of Mixed Numbers

Introduction

Estimating the sums and differences of mixed numbers is pretty much the same thing like estimating the sums and differences of proper fractions. The only difference is that you will have a whole number in mixed numbers. So, once again, all you have to do is either round the fraction to 0, 1/2, or 1. That is the main method of getting your estimated sum or difference.

Estimating Sums and Differences: Example

Let's say for instance that we have a problem such as 2 3/5+6 2/9.
Remember that we'll round the fraction. In 2 3/5, 3/5 can be rounded to 1/2. In 6 2/9, 2/9 is closer to 0. This now makes the fractions 2 1/2+6. If 1/2 is converted to .5, we can do 2.5+6, which equals 8.5 or about 8 1/2.

Therefore the estimated sum of 2 3/5+6 2/9 is 8 1/2.

Sheet 1 Practice Problems on Adding and Subtracting Mixed Numbers