SpeQ Mathematics - SpeQ is a small, extensive mathematics program with a simple, intuitive interface.
hackattic - No nonsense, real world programming challenges
Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.
HackerRank - HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.
NumWorks - The graphing calculator that makes learning math easier.
Takehome - Effective and humane coding challenges for candidates