MIT OCW has quite a few mathematics courses listed. Many of them rely on textbooks, but one might be able to find the books used or borrow them from libraries if one can’t afford or just doesn’t want to purchase them.
Khan Academy might be useful if one wants to build up a more basic foundation, but it looks like the highest level of their offerings consists of differential equations and linear algebra.
MIT OCW has quite a few mathematics courses listed. Many of them rely on textbooks, but one might be able to find the books used or borrow them from libraries if one can’t afford or just doesn’t want to purchase them.
Khan Academy might be useful if one wants to build up a more basic foundation, but it looks like the highest level of their offerings consists of differential equations and linear algebra.
Thank you.