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Facebook Math problem - have we discussed this, math gurus?


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Does this problem have more than one correct answer?
6/2(2+1)

 

Following BEDMAS, I got 9. But one of my kids said if you set the division problem up like a fraction, the answer could be 1.

 

What does the Hive say?

Edited by KathyBC
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Does this problem have more than correct answer?

6/2(2+1)

 

Following BEDMAS, I got 9. But one of my kids said if you set the division problem up like a fraction, the answer could be 1.

 

What does the Hive say?

 

The point of mathematical language is to avoid ambiguity, not to create it. No mathematician would ever write an expression like that with the goal of "tricking" students.

 

If the (2+1) is intended to be part of the numerator (i.e. multiplied), it would be better written as

6(2+1)/2

or

(6/2)(2+1)

 

If the (2+1) is intended to be part of the denominator (i.e. divided), it would be better written as

6/[2(2+1)]

 

Also, math is not usually well-expressed in ordinary type-writing. Far better to use handwriting or software designed for mathematical expressions so that spacing and positioning can reinforce the meaning of the expression rather than obscuring it.

 

That said, as written, the expression would best be interpreted as

(6 / 2) * (2+1)

which is 9.

 

But I can't stand these types of problems. They seem to reinforce to the general public that math is just a collection of weird rules that some people "get" and some people don't.

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I agree with Cosmos that it is a very poorly written, ambiguous equation.  

It could reasonably be read either way, and therefore utterly fails at its job of communicating mathematical meaning.

 

If (2+1) is in the numerator:

6/2(2+1)

6/2(3)

3(3) = 9

 

If (2+1) is in the denominator:

6

----

2(2+1)

 

6

----

2(3)

 

6                3

----   OR   ----    = 1

6                3

 

Wendy

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Good point, Cosmos: simplest explanation is usually least ambiguous. I thought the point of these Facebook posts might be to get people thinking about math as part of their day-to-day lives, but judging by the comments posted on Facebook, it's apparently to give people an excuse to insult each other. (roll eyes) I was sure the discussion on here would be more thoughtful. :-)

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