gdcalc is a financial, statistics, scientific and programmers calculator for Unix. The GUI was written with glade(1) and uses the Gnome/Gtk+ toolkit - so it may well be compatible with themes and other whiz-bang features of those systems. gdcalc has both Algebraic notation (ie. conventional, TI or Casio style) and Reverse Polish Notation (RPN or Hewlett-Packard style). If you've not heard of RPN before, you are probably familiar with algebraic calculators. Very briefly, while simpler and more natural to use, RPN calculators need some study eg. they have an Enter key instead of the equals key.