casual interview, friendly manager, maths test during the interview, requires smart casual dress code, relatively easy, quick process overall, no complaints with the process at all, I received a reply within a few days

It was talking about yourself, and experience. After just talking, you're given a test page with about 10 equations to solve on it. It was rather easy, no hard questions. I think one was like 17+35, which is something you get to know like the back of your hand in training, but it wasn't hard.