It was overall fine, but I would say that in fact it was focused on previous experiences and internships and any other related experience. The best way to prepare is definitely to be ready for the classical walk me through your resume questions. Why did you live your previous position. The interviewer was calm and friendly. You are given hints if you get stuck. I made minor mistakes in mental maths in almost every question yet got through to round 2, which suggests that they are more interested in whether or not you know how to solve problems