50 pages in, I decided to take a step back and read a calculus book first, but wait my algebra and trig are crap so back to the basics. So yesterday I hit LCM and GCD applications and factoring which are very basic. So, I'll probably resume the initial book in a couple of years or so...
With these you should be able to follow the Feynman lectures or watch the very fine „Theoretical Minimum“ series by Susskind (http://theoreticalminimum.com)
I'm doing a full review of mathematics at the moment. Not in depth, more of a "here's an application of the GCD function" so I know what tools to use to solve specific problems. All this is beneficial for the day job as well who expect to see some value from my time spent even though I'm not being totally honest with the objective to them. Realistically I want to think abstractly in the terms of mathematics and develop some intuition.
Was completely unaware of the Theoretical Minimum series. Thanks for that.
Edit: I'm reading Mathematics: From the birth of numbers by Jan Gullberg as a text. Wonderful book. Covers just about everything and is beautifully written by a non mathematician with no assumptions spared and no education target. In fact the forward is mainly bitching about the education system. Slightly worried I will get distracted by this book but that's never a loss!
Over 1000 pages is quite a long read, though. I never managed to read a (science) book as big as that from cover to cover myself. One thing I learned through the years is to never use only one book for learning. Books have different styles and not every style fits to every student. Additionally one book might be good at one specific topic and weak on another. So nowadays I always use a couple of books (or online resources) to learn a new topic.
One suggestion: make sure you don't just read about math, but also try solving exercises and problem. These are very important for actually learning the material.
Agree with solving problems; this was what was missing from my school education. Literally rote and box ticking with zero applications.