Possible Duplicate:
What is 48รท2(9+3)?
Please, look at the picture?
Which calculator shows true result and how to prove achieved result?
$\endgroup$ 63 Answers
$\begingroup$Despite every personal belief, a notation like $a/b(c+d)$ is ambiguous. At school I learned that this should be $$ \frac{a}{b}(c+d), $$ but even in research papers somebody could read $$ \frac{a}{b(c+d)}. $$
$\endgroup$ $\begingroup$when two operations have same precedence, then the operations are done from left to right.So here, division is done first and then multiplication.This is just a convention.Without this, this expression is ambiguous.
$\endgroup$ $\begingroup$The reason why calculators are giving different results is because one is calculating,
$$\frac{6}{2\cdot(2+1)} = 1$$
while the other is calculating,
$$\frac{6}{2}\cdot(2+1) = 9$$
Depending on what you want to calculate, you could obtain different answers.
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