May 22nd

May 22nd

Estimating Sums and Differences of Mixed Numbers

When adding or subtracting mixed numbers, we can check by estimating, determining whether our estimate and our answer are close. Note that when we round mixed numbers, we round to the nearest whole number.

Checking a Sum by Estimating

Checking a Difference by Estimating

EXAMPLE

Combine and check:

Solution

We begin by adding the first two mixed numbers:

Next, we subtract from this sum.

So .

Now let’s check this answer by estimation.

The estimate, 7, is sufficiently close to to confirm our answer.