It was an intense process but not intimidating. It was very selective to get to the first round which was held on campus. First round is two 45 minute interviews. They both are 5-10 of behavioral, a 30 minute case, then some time for questions. Mine were on very specific problems I had no prior knowledge on but the interviewers were helpful. Some math involved that required a scratch sheet. A couple graphs or charts in both to analyze. The final round was at the home office. Two people from BCG offered to run cases with me on the phone and one of my first round interviewers gave me feedback in between. Everyone was supportive and wanted me to do well. The final round was the same two 45 minute structure. It was meant to be more conversation. Mine had a lot less math than the first round, just a couple charts to talk about. One was a real BCG case.