Math problem, but I think it is more appropriate here

[Averagesupernova]

This problem is floating around the web:
6 / 2(1+2)
A disappointing number of replies say the answer is 9. Where I come from the answer is 1. Now I will be the first to admit that I maybe I am wrong. But what is disheartening is the number of people that are on each side of the fence. If one out of 10 said the answer was 1 I would question my own answer more than I have. Or, conversely if one out of 10 said the answer was 9. But no matter how you slice it there are enough people with wrong answers out there that it really disappoints me.

 

[EnumaElish]

Logically it's 9. Typographically it may be 1. If I thought "/" means "times seven" then it'd be 1,764 I think.

 

[dkotschessaa]

There's a good article here on PF that a mod wrote that talks about this type of thing floating around. I can't find it at the moment. Here's another: https://www.wyzant.com/resources/blogs/236411/the_order_of_operations_pemdas_bodmas_that_you_learned_in_elementary_school_is_wrong

IMO these things are written badly on purpose, and are mostly a waste of time.

 

[Averagesupernova]

The way I see it is if you replace the 2 inside the parenthesis with an X and assign either 1 or 9 to the other side of the equation and solve what will X be? This would be a pretty basic algebra problem that everyone would agree on. Yet when it is presented as I showed in the first post it is unacceptable?
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If a mod thinks this should be moved I would have no problem with it.

 

[Mark44]

The way I see it is if you replace the 2 inside the parenthesis with an X and assign either 1 or 9 to the other side of the equation and solve what will X be?

There is no "other side to the equation." What you wrote is an expression, not an equation. An equation always has = in it.

This would be a pretty basic algebra problem that everyone would agree on. Yet when it is presented as I showed in the first post it is unacceptable?

With or without x, the expression is still ambiguous.

 

[dkotschessaa]

The way I see it is if you replace the 2 inside the parenthesis with an X and assign either 1 or 9 to the other side of the equation and solve what will X be? This would be a pretty basic algebra problem that everyone would agree on. Yet when it is presented as I showed in the first post it is unacceptable?
-
If a mod thinks this should be moved I would have no problem with it.

I think part of what makes this and other problems look ambiguous is the single line notation we resort to when using text only as a means of writing. Now watch me be Mr. Fancypants and use LaTex:

$\frac{6}{2(1+2)}$

ooh now it's pretty. It's also a lot less confusing, and I imagine that semi-numerate people would get the same answer if it were written that way. In fact when it's written like this I'd probably cancel the 2, turn the 6 into a 3, then I'd have $\frac{3}{3}$ which is easier for me.

(Of course, this is looking elementary now, but with bigger numbers especially you could see the advantage).

-Dave K

 

[Mark44]

This problem is floating around the web:
6 / 2(1+2)
A disappointing number of replies say the answer is 9. Where I come from the answer is 1.

If it is written as $\frac 6 {2(1 + 2)}$ then I would agree that this simplifies to 1.

As written, though, most would say that this simplifies to 9, according to the usual rules of precedence.

Now I will be the first to admit that I maybe I am wrong. But what is disheartening is the number of people that are on each side of the fence. If one out of 10 said the answer was 1 I would question my own answer more than I have. Or, conversely if one out of 10 said the answer was 9. But no matter how you slice it there are enough people with wrong answers out there that it really disappoints me.

 

[Mark44]

Thread closed. There have been numerous threads here about this. One of them is here: https://www.physicsforums.com/threads/482-9-3-and-similar.494675/