9

1

1

9

1

1

6/2(1+2) can also be noted 6/2*(1+2) or 6/2*3 = 9 (left associative operation)

If it was noted like this 6/(2(1+2)) or 6/(2*(1+2)) or 6/(2*3) = 1

But, that is the current accepted way to do it I think and it is understandable that people get confused, especially older ones. The answer 1 would have been regarded correct a long time ago. More than today...

That's how I was taught to do it, 40 years ago, I saw that and I immediately compute it as 6/(2*(1+2)) as we were told to first compute the term with the parenthesis associated to the multiplication operator, in this case. And it is probably still a valid answer as the whole thing is ambiguous and methods used slightly change in different parts of the world (I'm in Belgium).

Also, some calculators and programming languages require parentheses around function inputs, some do not apparently, adding to the confusion. So, people using google calc or a specific HP model or a specific TI model, etcetera, may get a different answer...

I'm not a mathematician, so I don't know if some of them still consider the answer 1 as valid. I don't know. One thing is certain, it is a rabbit hole when you start digging into it. As a starting point :

https://en.wikipedia.org/wiki/Associative_property

So if you said 1, well, it probably still is a good answer, depending on how you were taught in school. From the few snippets of information I found, it is still not clear cut, believe it or not. I have to learn math again, my brain is rusted.

Catholic school in the late 70's taught me the answer is 1