By recommend, I mean content you actually find to be high quality, well done, and easy to absorb and follow. By relearn, I mean I have forgotten everything I ever learned in high school.
If you graduate to college level you can try Opencourseware -> https://en.m.wikipedia.org/wiki/OpenCourseWare
I haven’t looked for math classes but I just found classcentral.com last night. They have an unbelievable number of free classes, like tens of thousands. Seems geared to earning actual certificates etc. but I found tons of computer classes and the one I focused on and watched several chapters was excellent. Very clear and easy to follow. Seems a little hard to find anything TBH - any search returns a flood. But who knows, worth a look.
In the past I wanted to do the same because I have the same problem as you but I never actually gotten around to executing the learning part… The one resource that picked my attention the most is https://youtu.be/didXE0HkSC8 ("Learn Mathematics from START to FINISH (2nd Edition) "). It’s a 37 minute video with dozens of book recommendations and how you should proceed with the order of those books.
