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Join Date: Aug 2011
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Re: 6÷2（2+1）=？
The basic rule for multiplication and division are:
-Multiplication and division have the same priority
- Addition and subtraction have the same priority
- Multiplication and division have higher priority than the addition and subtraction
- Operations of the same priority are implemented from left to right if there is no brackets to change the priority
and that's the only rule I accept.
By these rules we have:
6:2·(2+1)= 6:2·3=3·3=9
Problem appeared because the obelus ÷. The obelus, the name for the symbol denoting “÷”, is argued by some to represent the division of all terms preceding it by all terms after it. The obelus supposedly separates the two components of the fraction, with the top dot representing the numerator and the bottom dot representing the denominator.
So they count like this:
(6)/(2·(2+1))=6/6=1
But ISO states that the obelus should not be used.
So the answer is 9.