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Video: Rounding Mixed Numbers to Whole Numbers to Estimate the Addition/Subtraction of Mixed Numbers

Kathryn Kingham

By rounding each term to a whole number, estimate 7 2/3 + 4 1/12.

01:37

Video Transcript

By rounding each term to a whole number, estimate seven and two-thirds plus four and one twelfth.

Here’s what we’re trying to estimate. Before we can estimate, we need to take each of these add-ins and round them to their nearest whole number.

Let’s start with seven and two-thirds. When rounding to the nearest whole number, the seven will either stay the same or go up to eight. Seven and two-thirds is slightly closer to eight on a number line than it is to seven. This means that seven and two-thirds rounded to the nearest whole number is eight.

We need to follow the same process for four and one twelfth. We’ll either round it to four or five. Four and one twelfth falls closer to the four than to the five on a number line, which means that four and one twelfth rounds to the nearest whole number as four.

Now we can estimate the addition problem. Eight plus four equals twelve. Seven and two-thirds plus four and one twelfth is about twelve.