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October 22nd, 2014, 07:16 AM   #1
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Multiplication or Division in Daily Life Problem Which Involves Negative Number

Can anyone give me some examples of daily life problems which involve negative numbers in multiplication and division? One for multiplication and one for division. Thank you very much.
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October 22nd, 2014, 07:26 AM   #2
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Dividing loan payments over a number of periods, perhaps?
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October 22nd, 2014, 07:36 AM   #3
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I don't think negative numbers are used much in daily life. The only examples I can think of are temperature scales, but they are rarely involved in multiplication and division calculations. Furthermore, most examples can be made positive by considering losses or bills rather than gains.

One example could be related to depreciation in value of a car.

i) Over the years 2000 - 2005, a car devalues in price from £3400 to £3250. What was the change in value?
ii) Over the years 2005-2010 the car devalues again by 2.5 times the amount that it devalued in the preceding five years. What was the change in value in the car over the time period 2005 - 2010?

You can make a similar division problem with this too. In fact a division problem might be more realistic since a car typically devalues more slowly over time.
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October 22nd, 2014, 09:47 AM   #4
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Uh, sorry, I forgot to mention that it was aimed for Middle Schoolers. Aren't those examples too complicated for them? Thanks for the inputs, though.
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October 22nd, 2014, 10:13 AM   #5
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A thermometer and forecast use negative numbers 4 - 5 months per year.

Also some settings on computer are given as negative numbers, like left_margin = -0,6.
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October 22nd, 2014, 10:25 AM   #6
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Any measure that (sometimes) is negative could be averaged. That would give a division problem.

Similarly, if the average of 4 measurements is -3, and the 5th measurement is -2. What is the new average?
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October 22nd, 2014, 02:56 PM   #7
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And what about the multiplication example?
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October 22nd, 2014, 05:30 PM   #8
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The second one of mine involves multiplication.
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October 22nd, 2014, 05:31 PM   #9
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Let me google that for you
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October 23rd, 2014, 09:19 AM   #10
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If you want (as example) to teach how to divide 1000 by -77,
why do you want to create a useless "word problem story",
as generally seems to be the case way too often as far as I'm concerned.
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