Data stats for r/learnmath

Post all of your math-learning resources here. Questions, no matter how basic, will be answered (to the best ability of the online subscribers). --- We're no longer participating in the protest against excessive API fees, but many other subreddits are; check out the progress [among subreddits that pledged to go dark on 12 July 2023](https://reddark.untone.uk/) and [the top 255 subreddits](https://save3rdpartyapps.com/) (even those that never joined the protest).