The ones that it's difficult TO prepare for. Memorising quotes for English is a [bleep]. Maths is just memorising formulas and knowing how to use them, I guess. I don't see why higher levels of maths can't be given formula sheets like general classes are. It's not like there'll be a situation in life where you can't just check a bit of paper to make sure you don't majorly [bleep] up some calculation.