However, another student said the exam was "not as hard as people claim. In my opinion, the previous year's papers were a lot harder than yesterday's exam," he wrote.
An anonymous Year 11 student said he or she "did find the exam hard" but it "covered everything we have learnt throughout the year, but on a difficult scale".
"This year's math examination was a proper examination and not an exam where students cram formulas and spew them onto the paper," the student wrote.
An Onehunga High School student said sample questions provided by NZQA were "very similar to the questions in the exam".
A Year 9 student, who sat the exam two years before the usual time, said most of her class "answered all the questions, with a few exceptions".
"We worked extra hard, as we were worried that we were going up against people two years older than us. We ... therefore found the exam not that difficult," she wrote.
However, Jake Wills, Kāpiti College head of maths who is co-ordinating the open letter to NZQA, said two questions required material from Level 2 of the maths curriculum.
One of these, published in the Herald, asked students to calculate the distance between two holes in a swing attached to two sides of a rope hanging from a bar. Some readers complained that this was impossible to answer, but this was because the Herald did not realise that the answer relied on a previous part of the question which provided an equation for the shape of the rope.
Using this equation, Wills calculated that the two holes in the swing were 2.225m and 3.775m to the right of the left-hand top of the rope, making the holes 1.55m apart.
The second question provided a graph showing how many males and females were charged with reckless driving. Altogether 215 males and 83 females were charged, so males were 2.6 times more likely to be charged than females.
The Herald also published a third question which Wills said was within the Level 1 curriculum, asking students to calculate the angle at the top of a kite inside a square.
The question stated that the two longer sides of the kite were the same length as each other and of the same length as the distance between the top and bottom of the kite.
Wills deduced that, since the distance from top to bottom of the square is the same as the width of the square, the width of the kite at its widest point must also be the same length as its two longer sides.
He then bisected the kite horizontally and vertically to split the kite into triangles, and used rules about angles within equal-sided triangles to deduce that the angle at the top of the kite was 150 degrees.