Exams that don't make sense
Extra checks have been ordered on exam papers after thousands of students were given questions that were impossible to answer.
The mistakes happened in three different AS-levels taken by students in England, Wales and Northern Ireland.
The exams are normally taken by pupils in Year 12, aged 16 or 17.
The errors affect tens of thousands of students, who might need to get certain results to get offered a place at university.
The people in charge of the exams have been told to carry out extra checks on any exams that haven't been taken.
They say they will make sure no-one who's done the exams with the impossible questions loses out on marks.
But students who took the exams are upset because they say they lost time trying to work out the answer of the impossible questions instead of doing the rest of the test.
The mistakes included maths and business studies questions where there wasn't enough information to solve the answers.
There was also a biology question which gave several possible answers but none of them were right!