That brings back some very fond memories. I was in 6th form in school doing double maths and physics A-level (in the UK – that’s about 17 years old) and bought a Sinclair Scientific by mail order.

A scientific calculator usually has special buttons for parentheses, trigonometric functions, exponents, inverses and pi -- among other things. A graphing calculator does even more.

The iPhone's scientific calculator provides exponential, logarithmic and trigonometric functions. It even has some hidden functions that reveal themselves if you hit the button that reads ‘2nd'.

It laughs at splashes, dust and shocks. It eats military-spec drop tests for breakfast. It’s ideal for math in the great outdoors. Meet Casio’s new ruggedized scientific calculator, the fx ...