The interview process consists of multiple stages. The first one is a numerical test, followed by a phone interview. The numerical test was ok and - at least in the case for the role that I applied for - not that tough. If you have done a few practice tests that are available online it should't be too hard. Next was a phone interview with the direct manager. This is was the last stage for me as I realized that this role was not suitable for me at all. Also, I felt like the actual job had not so much to do with the description in the job ad. Likewise, my interview partner realized that I was not the right candidate as they were looking for a more numerical/technical person.