I have both the FX-991ESPLUS and FX-991EX. For A-levels, you won't need anything more than FX-991ESPLUS. The newer version (FX-991EX) has features which aren't really used in A-levels such as solving 3 simultaneous equations, equations with X^4, and I think they increased the memory capcity so you can generate larger tables. They also changed the interface completely, and made it with graphical menus which is pretty confusing and it was hard getting used to after using the older versions. However, in my country the price of both calculators are the same. So I'd rather buy the newer one because it's more future proof (can use it in uni).