Calcoo is a scientific calculator designed to provide maximum
usability.  The features that make Calcoo better than (at least some)
other calculator programs are:
* Bitmapped button labels and display digits to improve readability.
* No double-function buttons. As the result, you need to click only one
  button for any operation (except for arc-hyp trigonometric
  functions).
* Undo/redo buttons.
* Copy/paste interaction with X the clipboard.
* Both RPN (reverse Polish notation) and algebraic modes are available
* Tick marks to separate thousands.
* Two memory registers with displays.
* Displays for Y, Z, and T registers.
* It is a purely scientific calculator. There are no buttons for the
  hexadecimal digits (ABCDEF) and logical operations, which take space
  and distract from "scientific" buttons.

Homepage:
https://calcoo.sourceforge.net/
