Phone interview first where you answer a little about your background and then mainly helps answers any questions you have. Next round is individual interviews with people in the office you prefer.

First round was a 20 minute PowerPoint presentation of a case you are given beforehand. The interviewers interrupt to ask questions and that may mess with the flow of the presentation. They ask about the maths, the solutions provided, and your thought process. They also ask about personal experience but it takes less time than the presentation