I'm in that boat... I only took up through Calc I originally and even that was so long ago that I've forgotten most of it. So I'm working on a self-learning plan to go through Calculus (equivalent to traditional Calc I, II, III courses), Linear Algebra, Differential Equations, and Probability / Statistics. I can share some of what I've been using.<p>1. The "Mooculus" Calc class via OSU / Coursera. <a href="https://mooculus.osu.edu/" rel="nofollow">https://mooculus.osu.edu/</a><p>I've found this to be useful, but the videos are all really short and the content is kind of "choppy". That is, it jumps around quickly, giving small nuggets of content, and doesn't flow super well. Still, there's some good stuff in here.<p>2. "Professor Leonard" on Youtube. <a href="https://www.youtube.com/user/professorleonard57/playlists" rel="nofollow">https://www.youtube.com/user/professorleonard57/playlists</a> I'm going through his Calc I sequence now. This is basically a traditional college class, just recorded and put on Youtube. Flows better than the Mooculus class as a result. Leonard is a good lecturer and keeps things interesting. He has videos series on Calc I, II and III, Statistics, as well as pre-calc / intermediate algebra, etc.<p>3. Gilbert Strang's Calculus lectures on Youtube. <a href="https://www.youtube.com/watch?v=X9t-u87df3o&list=PLBE9407EA64E2C318" rel="nofollow">https://www.youtube.com/watch?v=X9t-u87df3o&list=PLBE9407EA6...</a> Pretty good explanations of Calculus concepts, at least up to where I'm at (somewhere near the end of the section on differential Calc, just before the stuff on integration starts). Strang also has a very famous series of videos on Linear Algebra, but I haven't gotten to those yet.<p>4. MathBFF's Youtube videos. <a href="https://www.youtube.com/user/mathbff" rel="nofollow">https://www.youtube.com/user/mathbff</a> Short videos covering specific topics: how to evaluate limits, how to use the chain rule, etc. Helpful for an alternative explanation of a concept you might need more help with.<p>5. Khan Academy. <a href="https://www.khanacademy.org/" rel="nofollow">https://www.khanacademy.org/</a> Everything from basic arithmetic up through Linear Algebra.<p>6. On Coursera there is a series of classes in a "specialization" titled "Statistics with R" from Duke University. I've done the first 3 of those and they've been very useful for both learning Statistics / Probability, as well as help ramp up my R knowledge.<p>I also have a whole pile of "dead tree" books I consult, ranging from traditional college texts (mostly acquired for dirt cheap at used book stores), to those high-school AP test study guides, to a bunch of books in the "For Dummies" series (eg, "Calculus I for Dummies", "Linear Algebra for Dummies", "Differential Equations for Dummies", etc.), and the like.<p>Edit:<p>I almost forgot. If you get stuck, there are various forums where you can ask questions / get help, like:<p><a href="http://math.stackexchange.com" rel="nofollow">http://math.stackexchange.com</a> (note, this is different from MathOverflow, which is more for research level questions and answers)<p><a href="https://www.reddit.com/r/learnmath/" rel="nofollow">https://www.reddit.com/r/learnmath/</a><p><a href="http://reddit.com/r/cheatatmathhomework" rel="nofollow">http://reddit.com/r/cheatatmathhomework</a><p><a href="https://www.reddit.com/r/homeworkhelp" rel="nofollow">https://www.reddit.com/r/homeworkhelp</a><p><a href="https://www.reddit.com/r/askmath" rel="nofollow">https://www.reddit.com/r/askmath</a><p><a href="https://www.physicsforums.com/" rel="nofollow">https://www.physicsforums.com/</a>