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Possible Duplicate:
What is 48÷2(9+3)?

Sorry if this has already been asked, my searches were fruitless...

There's been a buzz lately about the different results given by two different Casio brand calculators for the same expression. It would seem that there's debate on this issue.

The expression is thus:

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

It would appear that the debate is between the scope of the division operator in the equation. Now, as a software developer, I'm accustomed to well-defined operator precedence. The compiler knows exactly in what order terms will be evaluated. Thus, above, the answer is 9.

However, it would appear that the two calculators differ because there's debate about that division operator regarding whether it divides the entire expression or only the first two terms. Rather, is it:

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

or is it:

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

Is there an official answer regarding the operator precedence for mathematics in general, outside the realm of computer programming and compilers?

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    No, there is no official anything in mathematics...2012-03-30
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    @MarianoSuárez-Alvarez: I wonder what the community's take is on the statement from the referenced article: "Mathematics abhors a contradiction; they cannot both be right."2012-03-30
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    @ZevChonoles: Fair enough. I struggled for a bit wondering if this is even truly on-topic or constructive for this site. Couldn't hurt to try, I suppose.2012-03-30
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    @David, they *can* both be right, with respect to different conventions. And the already several years as a practising mathematician have shown me, everyone has her own conventions.2012-03-30
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    @ZevChonoles: Indeed, I have cast my vote!2012-03-30
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    @David: I didn't mean to imply that it's not on-topic and constructive; I just wanted to point out that the issue has been dealt with before.2012-03-30
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    To the mods in the room... Would you prefer that I delete this question outright, or leave it to be closed as a duplicate and directed to the original? I'm fine either way.2012-03-30
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    A calculator that interpreted it in the second way would drive me up the wall. (Then again, I’m not really happy with any non-RPN calculator.) I don’t recommend using the expression, simply the left-to-right convention for operations at the same level of precedence **isn’t** as general as it ought to be, but I do consider the second interpretation genuinely incorrect in the absence of a stated convention allowing it.2012-03-30

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