Calcpad
Free software for mathematical and engineering calculations
... such as calculation notes. It can help teachers to prepare calculation examples, papers, manuals, books etc. Students can use it to solve various problems, prepare homeworks, phd theses etc.
After installation, you will find in your documents folder a lot of examples for solving different mathematical, mechanical and structural/civil engineering problems.
If you like Calcpad, you can donate ♥ the project on GitHub and help for its development: https://github.com/sponsors/Proektsoftbg