Estimating Fractions/Mixed Numbers
Date: 01/10/2002 at 20:06:38 From: Lynn Subject: Estimating fractions/mixed numbers Hello, I need your help. I don't understand how to estimate fractions. Example: I am to find an estimated sum of 1/6 + 5/8, or 13 1/8 divided by 6 1/5. Please explain how I estimate an answer for these problems. Is there a formula?
Date: 01/10/2002 at 23:11:11 From: Doctor Peterson Subject: Re: Estimating fractions/mixed numbers Hi, Lynn. There can't be a "formula" for an estimate, since an estimate is by definition a deliberately wrong answer. You have to decide for yourself how accurate you want to be, and then decide based on the circumstances what it takes to get that level of accuracy as easily as possible. Perhaps you are being taught some techniques, but in the long run there is no right and wrong here. For your first problem, I would probably say that 1/6 is a bit bigger than 1/8, so the sum will be a bit more than 1/8 + 5/8 = 6/8 = 3/4. For the second, I would just drop the fractional parts, which don't make much difference, and divide 13 by 6. Then I'd simplify that and just call it 2. If I needed a closer estimate, I'd get a calculator! Mostly, estimation depends on familiarity with how numbers work, so you can judge what changes you can make that will not affect the answer much. One way to build that familiarity is to make a lot of estimates as well as you can (avoiding as much actual calculation as possible), and then compare with the actual answers. When you find you were far off, take a moment to ask yourself what went wrong, and what you could do to adjust your estimate. No "formula" can take the place of that sort of experience. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/
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