I recently interviewed at a Part 121 on demand freight operation... part of their process was a 60 question complex math test ...timed... answer as many as you can in 20 minutes...... some questions were aviation related... but most were complex calculations, meaning.. do one calc, then another.. then use the answers from those two to actually do another and answer the question.... I completed 30 questions... the two people who interviewed with me answered 15 and 18..... they were not overly difficult just complex and you had to be sure to read the whole question before you tried to compute the answer. It was quite challenging. I asked the Dir of Trng why they gave such a test, he said they felt there was a correlation in being able to answer questions like that under a time constraint and good decision making in the aircraft...ymmv.