A curly question in last week's NCEA Level Two maths exam has prompted dozens of complaints, with a university maths professor saying those who put the test together "messed up".
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The question asked students to work out the area of a section of a shape - but the answer was geometrically impossible.
NZQA said there were 34,465 students entered for Level 2 Mathematics and Statistics paper.
NZQA has received 27 questions so far, but while it has admitted there was an error in the question's design, it says that would not have prevented students from attempting it.
Dr Padraic Bartlett, a professional teaching fellow at the University of Auckland, said the problem had a couple of fish-hooks.
"One is that when you solve the problem you get something that is geometrically impossible.
"That is going to be a problem for really clever kids who are going to try and solve the problem and feel like it's impossible and then they're going to go back and check their working three or four times - that's going to be tough on them."
He said the way the diagram was written out was also misleading.
"I think that a lot of students are going to make an algebraic mistake here and it makes the problem much harder.
"So it's a thing where a mistake, a very trivial mistake that doesn't involve much change in your reasoning, makes it so much harder and it makes it harder for those students to do well even if they understand the material."
Dr Bartlett said the question's diagram was misleading.
"If you're trying to test teenager's understandings you don't label it like that - I don't think it's intentional, I think they just messed up."