ForgivingDivisionPart2

This is pretty droll.

Here's a parent asking Math Forum for help on his son's forgiving division homework:

From: Dan Bruce
Subject: Solving division problems using the "forgiving" method

My son has been asked to solve his division problems using the forgiving method, but he doesn't recall what this process is, and judging by the answers he's arriving at, he's way off base. Have you ever heard of this method and could you demonstrate it using the example 100/6?

Thanks.


And here's the answer:

Date: 05/15/2002 at 09:49:17
From: Doctor Mitteldorf
Subject: Re: Solving division problems using the "forgiving" method

I'd never heard of the forgiving method, and couldn't find references to it in our archives. From a reference that I found in a discussion group on the net, I gather that it's about piecing together whatever multiplication facts you are comfortable with to solve the problem at hand.

Suppose you want to know how many 6's there are in 100. You can remember that 7*6=42, so you write down the 7 as part of your answer, then take the 42 away from 100 and have 58 left.

Next step: you might say the same thing. There's another 42 in there, so there's another 7 sixes. Write down another 7 under the first one, and subtract 42 from 58.

Now you've got 16 left, and you know you can squeeze 2 sixes out of 16, but not 3. So you write down the 2 under your 7's and add them up: 7+7+2=16.

You've pulled 16 sixes out of 100 (with 4 left over that wasn't enough to make another 6). You did it in groups of 7, 7 and 2, but someone else might have done 5 and 5 and 5 and 1, and the "standard" method would have been to do 10 + 6. The method is forgiving in the sense that your partial guesses don't have to be anything in particular, as long as you don't overshoot.

- Doctor Mitteldorf, The Math Forum


+ + +


Yup.

I can just see all the extra learning about division and estimation that's going on here.

And so much less erasing, too!


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• Posted by: CatherineJohnson
• LogDate: Jun 05, 2005 @ 18:46