Saturday, June 7, 2014

Estimating the Sums and Differences of Fractions


Estimating is one of the most easiest things you do in math because all you are doing is just making a reasonable guess of what the answer can be. Just keep some of these key points in your mind for this topic:
  • Sum is the answer to an addition problem
  • Difference is the answer to a subtraction problem
  • Estimation is making a reasonable guess
  • Fractions must have a numerator and a denominator

Let's Try It Out!

Let's say that we have a problem such as 3/12 plus 2/6. All you need to do is figure out whether the fraction is close to 0, 1/2, or 1. In this case we have the following:
3/12 is closer to 0
2/6 is closer to 1/2
That means that all we do now is add our estimated fractions together: 1/2+0 which equals 1/2.
Therefore, our estimated sum for 3/12+2/6=1/2

To check your estimate, you can always do the actual problem and compare to see whether they're reasonable.

If you are having trouble figuring out whether to round to 0, 1/2, or 1, then I suggest using a number line, like the following:

Sheet 1 Practice Problems on Adding and Subtracting Fractions

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