It's best for simple calculations, however, it will perform some advanced operations, exponential and percentage calculations. One nice feature is that you can switch from the calculator mode to the text editor mode, highlight the "paper" view and copy it into a Word document.
It comes in both an Android and Windows version and uses a menu ribbon that functions like MS-Office menus. Work can be saved as file. When installed you have three choices: 1) free version, 2) Pro version or 3) register the program. It also has a free mobile version for Android. The versions for Mac and iOS systems are not free.
Download from the author's site HERE