I did the same as you, literally starting with the number line and basic factorisation around 10 years ago, using this book: https://www.bloomsbury.com/us/engin

I did the same as you, literally starting with the number line and basic factorisation around 10 years ago, using this book: https://www.bloomsbury.com/us/engineering-mathematics-9781352010275/ https://www.bloomsbury.com/us/engineering-mathematics-978135... It's designed for self-study, and it together with "advanced engineering mathematics" by the same author covers all the math from the first two years of a 3 year UK engineering degree (they don't have any gen ed requirements so my sense is the material covered is equivalent to the math from a US engineering degree. At some point, if you want to learn even more advanced math, you need to learn to do proofs, but you don't need a lot of mathematical knowledge to learn how to prove things, probably someone with a good high school math knowledge coupdnprsrn the basics, using a book like chartrand "mathematical proofs" which for the first five or six chapters only requires algebra knowledge. I now have an MS in math and statistics -self-learning is great, but once you get to the "proofy" math, it's really helpful to get feedback on your proofs from someone who knows what they are doing. I took some summer math classes at berkeley, and then did my MS at cal state east bay, and found that the teaching was much better at cal state, which I would guess is because they mostly don't get paid to do research (small sample I know, but talking to many friends doing math classes at berkeley, my experience seemed representative). So that kind of school (cal state) might not be the best if you wanted to do a top tier PhD (though every year we have a couple of people getting admitted somewhere for a math PhD program), but for actually just learning and intellectual satisfaction, it was great! I would second Khan academy, to quickly get an overview of a topic, it's great. But you don't really know something mathematical until you've done enough problems to be fluent in that area, which I think causes problems for some people who "understand" a topic but move on before they have "mastered" it IMO. Feel free to contact me if you want to chat or have questions