To do test tasks which give on interviews.
- Write a website for booking hotel rooms.
- Write a virtual filesystem access to multiple customers. Console application, service, WCF, tests.
- Write a window application for Windows which allows you to make new employees to the company. SQL, WinForms/WPF.
To do the job on the tutorial - https://chsakell.com/2015/08/23/building-single-pa...
Here is a super, Web API and SPA are popular. I took the splint on his website there's more.
Naguglit "real" job, the language is not important, in C# you can do almost everything.
And don't waste time on the nonsense about "what will the program", and "how much is 300 * 1252", etc.