As a former user of Sharps, I wasn't particularly open to the idea of changing to a Casio. However, having used the Casio for three yers now, for GCSEs and A-levels, I have fallen in love with the fx83es, and have purchased both an 85es and a casio graphical as a result.

The main selling point of the 33es is the natural display system - a calculator that can display surds! During examinations this is a fantastic boon - no longer are you looking for familiar decimal patterns - the exact surd is provided if avaiable.

The casio also possesses a decent memory, a good quality statistical mode, and a function mode, where one is able to map polynomial functions with defined domains, and hence gain their ranges.

The actual build of the calculator is very good - having survived in my bag for a good three years, being trampled by boys and text books on a daily basis. The screen is sturdy, with very little chance of leak, and is also scrollable, making large calculations easily manageable. One of the bad points with the sharp was that I found the keys would often stick, yet there is no such problem with the Casio.

Whilst the FX85es does have the additional solar power - a nice feature, the battery like on the 83es is fantastic, and I am yet to change the battery. One may argue that the 83 is no where near as feature rich as the fx99es (which is even capable of numerical differentiation and integration!) the fx83es offers superb value for money, and is the perfect calculator, especially for GCSE level students. I was able to pick the calculator up for £7 from tesco and £8 from school, and the price seems to vary around those levels.