the first round consisted of two 30 min interviews. 1 fit and 1 case interview. the fit interview was mostly resume walking and questions about any particular work experience or class that was interesting to them. plus the regular question of why consulting and why opera. plus any questions one may have about opera. the case interview for first round was conducted by a senior person and was a basic credit card annual fees question. whether the client should cancel it or not. nothing terribly new. it was quite short, and required some math. i guess in the first round they were mostly looking whether you would be a good "fit" and some basic logic and numbers skill. the second round, consisted of three 45 min each case interviews. the first had a brain teaser and a case involving some quant skills and the interviewer was sitting on data which you had to ask for or hint at looking into. the case was basically a supply chain related question about identifying cost cutting areas. the second case interview didnt have any numbers involved, and was mostly a strategic/dialogue types case about market entry. the third was also similar as in they want to see your skills in structuring a problem rather than showcasing math skills. the whole process was of average difficulty, but the strategic ones are hard to judge. as long as you hit the main points, things should go well. overall, the interviewers were quite friendly and supportive and willing to have a discussion rather than stressing you out. a big selling point of opera is the openess and friendliness among everyone which was mentioned by everyone.