A simple calculator with percent, scientific calculator, calculator with memory - all suitable to describe this application has a nice and functional interface, style Material Design, beautiful animation, sliding bar.
-Preview the course of calculation (long click on the button element is or history)
-Basic arithmetic operations
The choice of measures of angles: radians, grads, degrees.
History of calculations with possibility of choice of insertion of result or expression.
A good set of settings: the ability to choose how to fill the input window, multi-line or single line, disabling hibernation, and others. In the app there is advertising.