I applied online for the position and received an email a couple of weeks later with an invitation to an assessment centre. It consisted of 1 group exercise with a presentation, 3 one-on-one interviews and a problem-solving skill test. The group exercise wasn't hard and it is really no way to prepare for it. The presentation is 5 mins divided by 3 people so there is really not that much to talk about - be sure to stick to the requirements. Then I got into a room and the recruiters were coming in, one by one, to interview me. There were 3 interviews, each approximately 30 minutes. Very informal and pleasant, although I felt that they all asked me the same questions. Then there was a problem-solving skills test which consisted of 4 mathematical questions that someone read and I had to ask questions in order to get the information I need and solve the problem. It was very unusual and stressful to calculate something in front of the person assessing you, although the interviewer was very helpful. All in all, it was quite informal and pleasant experience. I got a call back the next day around 3 PM.