I remember doing combinatorics puzzles and number theory exercises in platforms like Brilliant when I had a bit of free time. All the while learning something. But the last time I tried Brilliant I did not enjoy it as much and I can’t afford it not anyway.
Does anyone have any recommendations of websites (or webrings), apps or games about or that touch on:
- combinatorics puzzles
- modular arithmetic puzzles
- concepts or exercises of number theory
If you like geometry and trig, the apps Pythagorea and Euclidea are very fun puzzles. They’re free and there are hundreds of puzzles. They get very difficult.