The Unit Converter app: easy, immediate and multi-platform.
Pebbles
An easy to use yet powerful calculator app
KBruch
KBruch is a small program to practice calculating with fractions and percentages. Different exercises are provided for this purpose and you can use the learning mode to practice with fractions. The program checks the user’s input and gives feedback.
Qalculate
Qalculate! is a multi-purpose cross-platform desktop calculator. It is simple to use but provides power and versatility normally reserved for complicated math packages, as well as useful tools for everyday needs (such as currency conversion and percent calculation).
GNOME Calculator
Calculator is an application that solves mathematical equations and is suitable as a default application in a Desktop environment.
Libre Office
LibreOffice is a powerful and free office suite, used by millions of people around the world.