I seem to recall that before I was interviewed I was asked to complete a short question paper. It was fairly basic questions to do with aviation related maths and mechanics. Pretty much the standard, "If I was flying at x knots to point A which is y nautical miles away, how long would it take? If I was burning fuel at x litres/hour, how much would I have left", type, and so on.
Nothing too demanding, basic arithmetic and a very basic understanding of aircraft physics.