BearCalc

Ths is a natural calculator that adopts the natural way of mathematical calculation. For instance, it uses the greek symbol pi instead of the letters "pi" to be the radian in the trigonometry functions. The symbol pi actually represents the number 3.14159 that could also be used in regular calculation. It does its best to conduct the calculation like the same way we do on the paper. It uses the graphical mathematics syntax and symbols instead of using strings like the other calculation apps do. It at least supports the following features

* It uses degree or radian for trigonometry function calculation
* It uses greek symbol pi intead of the letter pi to represent the radian
* It does mathematic fraction by having the numerator on top of the denominator separated by a horizontal line (the conventional way)
* It has the real square root calculation instead of using the square root symbol with the calculation "string" inside the parenthesis
* It saves the calculations to the history for later reuse (all of history entries could be deleted one by one or altogether)
* All of the calcuation equations could be reused and modified to form new equations for getting new results (just press on the right or left button after the equal button is pressed)
* It has calculation stage hihglight to help the users know where the cursor is at. For instance, if it is inside a fraction that is in a square root, it highlights the fraction and it highlights the square root once the cursor leaves the fraction and inside the square root again.

For more, please download it and try it for yourself.