The interview process was very interesting and filled with mathematical assessments.
Before even getting to a phone interview, you are required to take a numerical assessment. The numerical assessment was not overly difficult, but it requires you to get creative with the data given to get the right answer.
The phone interview is divided into two segments... a set of behavioral questions and then a case study. What I found difficult (and quite frankly, unreasonable) was the need to have memorized some algebraic equations that would be readily available using a resource, such as Google, in the real world. I felt penalized for admitting there was an equation available, but not knowing all of the variables needed to answer the question.
Beyond that, all of the personnel I communicated with were very friendly and professional.