Agreed with the comments about the fx991ES. In my opinion the best calculator that's allowed for A-Level, and I guess it works just as well beyond that(?) It's almost funny how much of a time advantage it gives you doing the grungy complex number bits of FP2 for example - where anything can be converted from Cartesian to polar form and vice versa. Also great in S2 for Binomial and Poisson distributions - just stick the formula in, give it some limits and watch it whir away!