| It really depends on what you're trying to do with the knowledge. If you mean learn it to the level of a university undergrad, then you'll need to do exercises and solve a lot of problems. If you're interested in computational or cookbook type math, then it's best to find some textbooks with lots of exercises and student solution manuals available. You can grab lots of homework problems, solutions, and lecture notes from undergrad material posted freely on the internet. I would also recommend learning about how to use some numerical packages or computer algebra systems, so you can check your work. If you're interested in proof based math, then it's probably best to find a grad student at a local school that you can pay to review your proofs and provide feedback. You might be able to use some online communities to do this as well. There are often books that are aimed at a very basic level and others that are aimed at a more rigorous approach for the same material. It can help to review the more basic or less rigorous books to help get some intuition when you're stuck or need an alternate explanation. There are several online math communities where questions about undergrad math have been asked and answered. A couple of examples for math and stats are: https://math.stackexchange.com/ and https://stats.stackexchange.com/ If you decide to follow an undergrad sequence of problems, you can look at starting with the highest level course you want and determining if there is any discussion on prereqs. You can trace the prereqs (which will typically be a subset of the previous course material) back to the beginning and find the minimal amount of material that you would need to get through. |