Pupils are resitting A-level maths papers as many as five times in their desperation to improve their results, official statistics have revealed.
Two of the most popular maths exams were taken at least twice by more than half of the pupils entered. More than 500 students sat one paper three times or more.
The figures, in a report for the Qualifications and Curriculum Authority, will fuel the row about whether exams are being "dumbed down".
The report is an interim evaluation on how changes to maths A-level, intended to make the exam easier, have affected take-up since they began in 2004. It provides the first detailed figures on resits for any exam.
Previously, exam boards have been reluctant to release data.
Figures provided by the OCR board showed that one student took a statistics paper six times.
On a pure maths paper, 3,257 of 6,258 candidates (52 per cent) sat the paper at least twice, while a further 314 (5 per cent) took it three times.
On a second similar paper, 3,052 (49 per cent) took it twice, while 511 (8 per cent) sat it three times.
More than 200 candidates resat two other papers at least twice.
The report acknowledged that "the scale of resitting is very large".
Brighter students, in particular, could be resitting modules even after they had achieved an A grade on a particular paper in their drive to achieve higher marks, it said.
This would then give them a better chance to gain an A grade overall.
Tony Gardiner, reader in mathematics at Birmingham university and past president of the Mathematical Association, said: "Retakes are a curse.
Universities should be allowed to make their offers based on the score that (students) get at the first attempt."
Dr Gardiner said that it was unacceptable that pupils resat easier AS papers many times, to try to score high marks, which could make up for the fact that they might not do as well in harder exams.
He said the resit culture worked against deeper understanding of the subject. Rather than taking some exams in Year 12 and then resitting, as happens now, they should take all exams after two years to allow them to master the subject.
The report said teachers were split about changes introduced in 2004, designed to make maths A-level "more accessible", after a dramatic fall in numbers taking the subject. Pupils allowed to take four of the easier AS papers and two harder A2 assessments, compared to the previous balance of three of each. Subject content was also cut.
Staff from 200 schools and colleges were surveyed for the report. Around half "view any moves to make the qualification more accessible... as unacceptable 'dumbing down'.
"Other teachers see the reduction in content as a positive move in terms of helping all students to succeed," said the report. It hinted that the second view might be favoured in any future change to exams, with further maths becoming the A-level of choice for high achievers.