Ask HN: How to learn math from zero for adults?

khan academy is the best for ANY age. Start from basic algebra and progress through trig, geometry, calculus 1,2,3 and linear algebra, and you'll be fine. That's what I did. Should take a few months depending on work ethic

Read the "mathematics for machine learning" book.

I went a similar route. What did it for me was conceptual analysis. You know how to program already. Maybe you did object oriented analysis? Once I understood, that creating a sample space can be understood as creating a class of the samples you expect, and then putting the attributes on an axis of a space, it clicked. Depending on the space, you then can visualize the outcome probabilities as weight of a point or area in the space. A random variable is then a mapping of that space to R etc. Or that differentiation is basically a way to get the slope of a function’s tangents at any point (it is differentiation of a function!) and its converse, integration, helps you find the area under a function graph. The important point is here that many interesting points can be mapped to doing this (for example calculating the probability from A to B, if you decided to represent it as area). I had worked with UML, OPM (object process methodology) and BFO (basic fundamental ontology) before. Asking “what is it (attributes, parts) and what can I do with it helps me a lot. The most important trait however was coping with frustration, sometimes it took me months to understand a concept.

I would say err on the side of too easy to begin with. Start with textbooks for high school (that you skipped). And master that before moving on.

Above is not advice but I would echo it, with emphasis that higher education makes much more sense when you go there as an adult with other stuff to do outside of it so uou just focus on learning things.