I did math a few years ago in college but I forgot most of it and now I have to relearn it to get into this program I'm starting in a few months.
I want to learn everything from the basics all the way up to the Calculus basically but nothing too advanced just very useful everyday math I can use to better my life.
I just really love learning stuff and math is so fun to me just being able to figure out algebra problems makes me happy.
It’s a super great service I bought it myself and find it fun to go through some of the courses on my free time. The logic courses are fun. The basic math courses do some cool explanations of divisibility rules. It’s quite a bit different than Khan Academy as it’s a lot less plug and chug, but instead it focuses on teaching small lessons and letting you use intuition and problem solving skills which to me are the fun parts of math. Besides Math it also has Computer Science, Physics, Probability, and other Sciences. I would recommend maybe trying it for one month maybe if they have a free trial or something and then decide if you want to sink the $599.99 into it. The month by month subscriptions are quite a bit cheaper, but if you want to use it long term it may be worth it to buy the lifetime subscription.
There's a Youtube channel 3Blue1Brown which is fantastic [1] as well. In fact, his videos are among the best if not the best for visually illustrating beautiful concepts in mathematics. The concepts covered are almost always widely applicable in problem solving and useful to know.
He's got a wide variety, but the series on Calculus and Linear Algebra are good refreshers for the two main subjects applicable to real engineering.
[1]: https://www.youtube.com/channel/UCYO_jab_esuFRV4b17AJtAw
Polya's How To Solve It is great for 'how to think like a mathematician'.
I love Knuth et al's Concrete Mathematics. Discrete maths plus jokes in the margins.
Stillwell's Mathematics and its History - meet the main strands of mathematics, their origins, and the great mathematicians.
Needham's Visual Complex Analysis - complex functions, differentiation & integration, Möbius transformations, hyperbolic geometry, vector fields etc - explained with a lot of pictures.
Although, you can check Combinatorics, Geometry, and Number Theory up to some point.
A good book I could recommend is Concrete Mathematics: https://en.m.wikipedia.org/wiki/Concrete_Mathematics