First sessions was mostly questions about things on my resume. (Describe the project, what did you do in detail, etc)
Second session was a quiz. Two questions on probability and the last one is writing pseudo code to implement a stack using only queue
Last session was first two math quiz, one on calculus and the other is to derive the mortgage amortization formula by hand. Then some general interview questions (what's your biggest weakness, why leave the last job, etc)