sipas (2/6/2013)
BODMAS says:B Brackets first
O Orders (i.e. Powers and Square Roots, etc.)
DM Division and Multiplication (left-to-right)
AS Addition and Subtraction (left-to-right)
It actually doesn't matter whether you do the division or multiplication first, but it's easier to keep track if you work left to right.
So:
2 + 5 x 6 / 10 = 2 + 30 / 10 = 2 + 3 = 5
2 + 5 / 10 x 6 = 2 + 0.5 x 6 = 2 + 3 = 5
Of course you should always remove any possible ambiguity by using brackets to make it clear what your intention is.
Actually it does matter. Within a given precedence level, always work left-to-right -- don't give precedence to an operation on the same level.
For example, take
8 / 4 x 2
The correct way is left-to-right:
8 / 4 = 2 x 2 = 4
If we do division first, we get the same answer, as it's still left-to-right. But if we do multiplication first, we get:
8 / (4 x 2 = 8) = 1
It's the difference between
8
-- x 2
4
and
8
-------
4 x 2
Edit: clarified a bit - and then corrected the spelling on the clarification.