Math coding project ideas?

Hi, can anyone recommend any IT projects in which mathematics plays a major role?

I am currently finishing low-level library implemenation in C++ that handles large floating-point numbers, which includes optimizations such as the Chinese Remainder Theorem and cryptographic tests for key generation.

This project is mostly just pure math, so I am looking for something where math will play a key role. I was thinking about some kind of simulation, but physical simulations like fluid or light simulation are not what I am looking for.

I would be grateful for any ideas.