A simple program for doing calculus with very large numbers.
This is sort of my pet project from a couple of years ago.
With some modifications it can calculate the factorial of very large numbers (the most I put through it was 1,000,000 and even that took several hours), so feel free to tailor it to your liking.
Two versions are provided, one in Serbian (my first language), and also one in English.
You may freely use this program for non-commercial and educational purposes.