Barely half the teens who attempted the critical NCEA numeracy exam earlier this year passed.
The result, a pass rate of 52 percent, was down from 57 percent for the corresponding testing period last year.
The Qualifications Authority said 82,900 students sat at least one of the three online tests offered in May and each test had about 60,000 candidates.
The pass rate for reading was 61 percent, the same as for the corresponding test last year, and for writing it was 57 percent, up from 55 percent for the same time last year.
The tests are the main way students meet compulsory NCEA literacy and numeracy requirements.
Those who failed could try again in September, or, if they were still at school, next year.
Qualifications Authority figures showed students from poor communities had the worst pass rates in the May round of tests.
Just a quarter passed the numeracy assessment and a little over a third succeeded in reading and writing.
In contrast, students facing the fewest socioeconomic barriers as measured by the Education Ministry's equity index had pass rates of 73 percent in reading, 68 percent in writing, and 70 percent in numeracy.
European students had pass rates of 72 percent in reading, 66 percent in writing, and 60 percent in numeracy.
Asian students' pass rates were 58 percent for reading, 55 percent for writing and 61 in numeracy.
Māori students' rates were 49 percent reading, 46 percent writing, and 36 percent numeracy.
Pacific students' pass rates were 41 percent reading, 43 percent writing, and 27 percent numeracy.
Year 10 students were the largest group of students, accounting for more than half the students who sat the reading and numeracy tests and nearly half the writing candidates.
They had higher pass rates across all three tests than other year groups.
Year 11 students were the next largest cohort, providing about a third of the teens attempting each test.
