Comment by kiechu

If you are far behind start with Khan Academy. Then there are MOOCs on Coursera and eDX as well. Less interactive but 100% Real deal (and it doesnt mean harder) are course materials often with videos from MIT Open CourseWare. If you are into ML do Gilbert Strang Linear Algebra. It will develop you so much that it can’t be understated. Buy his book and do exams and assignments. If you want to take pleasure in math there are brilliant channels on yt, for example Numberphile. GL man.