Tom wrote:
But it would help if more than 20% of primary school
teachers knew the answer to "what is one plus two time three".

My answer would be "do you mean one plus two-times-three, or
one-plus-two times three?"

Do I win an apple?

Are you the teacher?

Well, I seem to agree with the majority. :-P

Seriously, you can't claim only 20% 'got it right', as asking where
the brackets are is a perfectly reasonable (and imho, much more
sensible response than assuming there are none) question. Brackets
are very hard to hear in spoken questions. (I assume it was a spoken
question - if it was written it would be a slightly different matter)

Sorry, no cigar, nor apple.

There is a single correct answer without brackets.

Yes, there is a single correct answer without brackets. But if you speak
the question you can't tell if there are brackets that you can't see. It is
perfectly valid to ask.