SpeQ Mathematics - SpeQ is a small, extensive mathematics program with a simple, intuitive interface.
Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.
NumWorks - The graphing calculator that makes learning math easier.
Soulver - Soulver is a software application that functions as a calculator that allows you type a continuous stream of information rather than having to input data into multiple cells.
CalcTape - CalcTape is a revolutionary new kind of pocket calculator.
Calcbot for Apple Watch - Calculate, convert, and split tips from your wrist