Dynamic Technology Quantitative Researcher interview questions

1 round: quantitative researcher. Basically mathematical problems. e.g. number theory, probability and so on. The most difficult one I have come across. (more difficult than DRW and Optiver) 2 round: phone interview. Prepare now. So far I only have access to the screen test, and if I am free, I would say something about the phone interview. It requires you to complete 9 problems within 180 minutes, however, these problems are not multiple choices, so you ought to show how to derive them (and I think at least 4 of them requires strategy, process or proof) If you want to complete it in 3 hours, you need to leave at most 2 hour for thinking and calculating, and at least 1 hour for typing, correcting errors and so on. (Maybe the reason is that my native language is not English) I think at least 3 of them are so difficult that I could not solve one even now (1 week+ later). I think the background is rotating group. Yes, some classic quant interview come out such as A pratical / 150. However, you may find these books are helpless. These problems are new, such as some simple number theory and combinatorics (in quant interview I seldom distinguish them because the joint probability is high) are seldom recorded in such books. While in fact, these problems are just a package of some simple mathematical theorem in my own opinion. Good luck to u.