I'm a new old user of MHF. I'm 68 and a retired software executive. I decided to try to keep my mind sharp by learning new things on one of those things is understanding some theoretical physics I've encountered over the years. But in order to do that I have to understand the mathematics that supports it. And I've forgotten way more than I wanted to admit to myself. There aren't really many times one uses differential equations when trying to convince someone else half way around the world to buy a database management system to improve their business.
So I have gone all the way back to the beginning. I've purchased and have started Algebra I. I'm about 2/3rd's of the way through and find it fascinating that 1) I paid so little attention in 7th grade; 2) I remember much more than I thought I would; and 3) There are so many things I learned to do but didn't understand properly why I did them. I am really enjoying myself.
After Algebra I I'll take Geometry, Algebra II, Trig and Intro to Calculus. I did that in college and unfortunately foundered in Calculus. So most will be review but I hope to experience similar revelations to those I'm enjoying with Algebra I. Eventually, I hope to move onto higher math and its applications to quantum mechanics and relativity. But all that is a long ways away.
I'm here at MHF because the courses I'm taking are all video courses - most of them from "The Great Courses". The lectures are excellent and the course guidebooks are very good but there are questions that nag at me and aren't explained in the courses. I'm hoping others can fill in some blanks for me.
So, if you've gotten this far in my ramblings, really know the theory behind why we do certain things in mathematics and are willing to help, you're the resource I'm seeking.