There are many programs that calculate π.
Many are programmed using Java programing language but ones in C#, I don’t know.
Programming a π calculator is not easy, but this website http://staff.washington.edu/skykilo/Pi/Pi.html is useful.
Programming this calculator has some code that initiates the calculation process and another part that gets information to display, and another that actually displays all of the information.
These are some useful π calculators to use :