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Say i have the followingv operation - $6/3/6$, i get different answers depending on which division i perform first.

$6/3/6 = 2/6 = .33333...$

$6/3/6 = 6/.5 = 12$

So which answer is correct?

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    Many programming languages use the convention that operations with equal precedence are evaluated from left to right (except for exponentiation which evaluates from right to left) and these would interpret $6/3/6$ as $(6/3)/6 = .333\ldots$ or as $(6/3)/6 = 2/6 = 0$. With human beings, who knows? Henning Makholm's advice is most applicable in this case.2012-04-17

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By convention it's done from left to right, but by virtually universal preference it's not done at all; one uses parentheses.

However, I see students writing fractions like this: $ \begin{array}{c} a \\ \hline \\ b \\ \hline \\ c \end{array} $ Similarly they write $\sqrt{b^2 - 4a} c$ or $\sqrt{b^2 - 4}ac$ or even $\sqrt{b^2 -{}}4ac$ when they actually need $\sqrt{b^2 - 4ac}$, etc.

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    Doubtless no puns were intended in the comment above, except by the person who posted it.2012-04-17