calcoo

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.
* Undo/redo buttons.
* Copy/paste interaction with X 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.

Features that Calcoo lacks:

* Statistical mode.
* HEX mode.