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Old Oct 10th, 2012, 05:14 PM
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Re: 6÷2（2+1）=？

Order as I know it is:

parentheses 6/2(3)
multiplication 6/6
division 1

I'm surprised so many did division before multiplication giving 9

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Old Oct 10th, 2012, 05:26 PM
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Re: 6÷2（2+1）=？

1.

I said 9 before but I consulted my old textbook on parenthesis and I change my answer.

BOMDAS

Brackets off Multiply Divide Add Subtract.

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Old Oct 10th, 2012, 06:47 PM
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Re: 6÷2（2+1）=？

I thought it was 1 too but I was complacent and didn't think carefully

6 ÷ 2 (2+1) = 6 ÷ 2 x (2+1) = 9

The first and second expressions are equivalent

Quote:
Originally Posted by Morning Morgan View Post
Seriously the aim of these kind of questions is just to trick people, because with sufficient use of brackets all ambiguity can be avoided.
Agreed. Personally, I'm used to seeing and I'm used to using brackets for multiplication when that particular term is involved in addition/subtraction (eg. 6 + 2 (2+1) ). That's why I instinctively did "2 (2+1) = 6" in my head first. It's a reflex

If I had to write this particular expression, I would always use the multiplication sign to avoid any ambiguity (i.e. 6 ÷ 2 x (2+1) )
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Old Oct 10th, 2012, 07:04 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by silverwhite View Post
I thought it was 1 too but I was complacent and didn't think carefully

6 ÷ 2 (2+1) = 6 ÷ 2 x (2+1) = 9

The first and second expressions are equivalent

Agreed. Personally, I'm used to seeing and I'm used to using brackets for multiplication when that particular term is involved in addition/subtraction (eg. 6 + 2 (2+1) ). That's why I instinctively did "2 (2+1) = 6" in my head first. It's a reflex

If I had to write this particular expression, I would always use the multiplication sign to avoid any ambiguity (i.e. 6 ÷ 2 x (2+1) )
No. To avoid ambiguity, (6÷2)x(2+1) if the desired answer is 9.
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Old Oct 10th, 2012, 07:08 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by PhilePhile View Post
No. To avoid ambiguity, (6÷2)x(2+1) if the desired answer is 9.
It depends on how you see it. I personally prefer 6 ÷ 2 x (2+1)
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Old Oct 10th, 2012, 07:12 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by pov View Post
Order as I know it is:

parentheses 6/2(3)
multiplication 6/6
division 1

I'm surprised so many did division before multiplication giving 9
This isn't the correct order of operations though.
It is:
Parentheses
Exponents
Multiplication-Division
Multiplication doesn't go before division. Neither has precedence over the other. Same thing with addition and subtraction. They happen at the same time.
Then you just operate from left to right.

In this case we have 6 ÷ 2 (3) so the reason it's 9 is than you first have to do the division because it's on the left, getting 3 (3) =9.
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Old Oct 10th, 2012, 07:14 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by silverwhite View Post
It depends on how you see it. I personally prefer 6 ÷ 2 x (2+1)
There is no "personally prefer" in arithmetics, either you follow the rules or be as clear as possible.
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Old Oct 10th, 2012, 07:15 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by PhilePhile View Post
There is no "personally prefer" in arithmetics, either you follow the rules or be as clear as possible.
Explain how (6÷2)x(2+1) is objectively clearer
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Old Oct 10th, 2012, 07:23 PM
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Re: 6÷2（2+1）=？

I still don't get how you can put 2(2+1) as 2 x 3. I know the number outside the bracket means you should times it by what's inside the bracket and since brackets come first, shouldn't you do 2(3) before the division?

I don't remember them teaching us that you get marks for re-writing the question.
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Old Oct 10th, 2012, 07:24 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by Mary Cherry. View Post
I still don't get how you can put 2(2+1) as 2 x 3. I know the number outside the bracket means you should times it by what's inside the bracket and since brackets come first, shouldn't you do 2(3) before the division?

I don't remember them teaching us that you get marks for re-writing the question.
What's inside the brackets comes first
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Old Oct 10th, 2012, 07:24 PM
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Re: 6÷2（2+1）=？

The answer is 1, but if anything, this problem just demonstrates how stupid random math problems are.
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Old Oct 10th, 2012, 07:28 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by silverwhite View Post
What's inside the brackets comes first
Well yes, that's how you know to times the 2 by 3. I still don't get how you can rewrite the question and add the x in yourself though. The 2 is grouped with what's in the bracket, not with the 6.
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Old Oct 10th, 2012, 07:28 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by LoveFifteen View Post
The answer is 1, but if anything, this problem just demonstrates how stupid random math problems are.
Pretty much.

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Old Oct 10th, 2012, 07:30 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by Mary Cherry. View Post
Pretty much.

We can end the thread with that statement and the correct answer: 9.

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Old Oct 10th, 2012, 07:30 PM
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Re: 6÷2（2+1）=？

Quote:
Originally Posted by Mary Cherry. View Post
I still don't get how you can put 2(2+1) as 2 x 3. I know the number outside the bracket means you should times it by what's inside the bracket and since brackets come first, shouldn't you do 2(3) before the division?

I don't remember them teaching us that you get marks for re-writing the question.
That is multiplication then, not considered brackets anymore. You just do what is inside the brackets first.

Quote:
Originally Posted by LoveFifteen View Post
The answer is 1, but if anything, this problem just demonstrates how stupid random math problems are.
Can you please explain how you get 1?

As many people have said before (as myself) you do what's INSIDE the parenthesis (brackets) first and then divide and multiply. Since those steps come in the same order of PEMDAS (P, E, M&D, A&S to make it clearer) you do what comes first, i.e. LEFT to RIGHT.

6 divided by 2 and then 3(3) = 9
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