Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
HEXelon MAX - HEXelon MAX is a science calculator. It solves math expressions like: Sin(Pi)-Root(-8;3)+3.
draw.io - Online diagramming application
Console Calculator - Console Calculator is a powerful calculator with a simple console interface.
yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.
SpeedCrunch - SpeedCrunch. SpeedCrunch is a high-precision scientific calculator featuring a fast, keyboard-driven user interface. It is free and open-source software, licensed under the GPL. Download Documentation Donate .