I went through a total of three interviews. The first was a phone interview, essentially a screening call, that just went over my background and career interests. The second was an on-site interview with four members of the team. This involved an excel 'test' to see how I addressed problems. I was also asked a lot of 'word problems' in order to get a good look at my thought process. The third interview was another on-site interview with five members of the team, but three of them I had already met. During this interview I was asked to go through a few more word problems but the main part was when the two hiring managers used our thirty minutes to solely address my questions. I was then offered the position the following day.
Tip: If you get asked word problem questions, don't worry about getting the exact right answer. Just talk through your thought process and work it out out-loud. They are mainly looking to see how you problem-solve.