>>>Division and multiplication usually are processed left to right, so I think 12 is correct.
>>
>>This is right just for programming not right for classical mathematic. there is should be an extra parenthesis.
>
>I agree. I always try to use parenthesis to make complex expressions more readable, if nothing else.

I had wrong. A math. eng. friend of mine said that "left-to-right rule came from mathematics to computer".