When calculating by hand, it’s useful to have multiplication × (not dot, if you value your sanity at all) binding as tight as division / and multiplication-by-juxtaposition binding tighter than that. On the other hand, this only comes handy when your intermediate results are so large that one or two levels of (unambiguous) fractions still aren’t enough, and if at all possible you shouldn’t be communicating results that unwieldy. If you really need to, don’t confuse your readers and use some bloody parens. (You’ll probably need more than one kind.)

I see it as more important to realize that not all questions are well formed enough to have a right solution.

A test question like "6 / 2 (1 + 2) = ?" is not asking for the mathematical meaning of those symbols it is asking for "Guess what I as thinking when I wrote this".

(Unless it is a programming class and you are learning how the compiler reads your code)