Takapuna Grammar student Maia Brown said she could hear other students crying in the exam hall as they took the test.
The 15-year-old, who is in an accelerant maths class and usually gets merit and excellence results, said she did five mock exams before the test, but when she read the first question on the official test she knew she was "doomed".
"Most of it was things I hadn't seen, things we hadn't been taught," she said.
Many of the questions were vaguely-worded as well.
She was able to answer some achieved-level questions but "apart from that it was complete chaos".
"I felt really put out, really, I put so much effort into it and it seemed like all for nothing."
Classmate Barnaby Watts, 15, said he'd done "a decent amount of study" for the test but felt most of the questions "weren't really aligned with what we'd been taught".
He left the exam feeling like he had failed.
Thousands of Year 11 students struggled to answer questions in an NZ Qualifications Authority's MCAT (maths common assessment task) level one algebra paper that they say was vaguely worded and tested them on areas that had never been covered in class.
WHAT DOES IT MEAN:
Students who failed or wrote nothing on the test will miss out on four credits, and results may affect their class placements for next year.
NZQA does not hold re-sits. Benchmarking will finish this week and reveal whether the marking schedule needs to be adjusted if too many students did not do well enough.