NZQA Deputy Chief Executive Kristine Kilkelly initially defended the exam, saying on November 21 that the authority was "confident in the quality of the Level 1 mathematics examination".
But today she said she appreciated the time teachers had taken to contribute to the open letter.
"We value the professional viewpoint of teachers," she said.
"While it is not appropriate for NZQA to comment in detail on a specific examination while marking is still underway and before results are released, we do want to engage with teachers on the issues they have raised about the mathematics examination, following completion of the examination cycle."
The process of collating the open letter revealed that not all teachers agreed with the initial criticisms. Only "a number of teachers" - not all of the 118 who signed the letter - said they no longer had confidence in the maths examiners.
Some students also defended the exam, saying it was "not that hard".
But all 118 teachers signed up to "concern about the changes we see from year to year in the mathematics exams, when under standards-based assessments we are still assessing against the same standard".
"If large numbers of teachers from all around New Zealand feel that the examination did not meet the standard, then there is clearly miscommunication between NZQA and teachers about what the standard is supposed to contain," they wrote.
"Concerns were also raised that given there was a review into issues with the exams last year, and changes were supposedly made this year, that we may find ourselves in exactly the same position next year."
The agreed letter also expressed concern about the number of questions asked in the three papers making up the three-hour maths exam. Middleton Grange School student Evie Yeo said at the time that there were "far too many questions".
"You have to be doing an average of completing one page in five minutes, and there's no way this can be achievable," she said.
The open letter says: "If we want students to be able to demonstrate what they know, particularly if sitting all three papers, students should have enough time in the exam to be able to complete all three papers. Schools and students should not have to choose to only do one or two of the externals."
It asks NZQA and the Ministry of Education to clarify the standards, stop asking questions requiring knowledge from higher levels of the curriculum, and allow "an appropriate amount of time" to complete all the questions.
Kapiti College head of maths Jake Wills, who co-ordinated the letter, said NZQA had told him it would respond to the letter in 10 working days.
"I am pleased that they are taking it seriously," he said.
"Obviously we understand that to produce a good reply will take time, and we understand that they can't comment publicly while the marking process is still going on."
He said the signatures were gathered via the NZ Maths Teachers Facebook page and "a few other maths teachers' sites", but not formally through the NZ Association of Maths Teachers. The association is conducting its own survey about the exam.
