Solve different types of problems related to arithmatic, statistics, geometry, trigonometry, Booelan algebra, number theory...

Math Processor
Free
Offline
https://mathiversity.com/

Math Processor (MP) helps you solve different types of problems ranging from arithmetic to statistics, geometry, trigonometry, Booelan algebra, number theory and many other allied subjects. It is free and open source!
Besides the command-line, MP provides GUI tools called Easy Kits to make the core engine more accessible to less experienced users.