I really like Arthur Benjamin's work on mental mathematics. I'm not savant-level, doing division in the thousands or huge floating points in my head yet but I s

I really like Arthur Benjamin's work on mental mathematics. I'm not savant-level, doing division in the thousands or huge floating points in my head yet but I sure am a lot sharper than I was coming out of high school from studying his work, and I guarantee you will just have fun with expanding your capability to think about numbers. [1] I got a copy of this book from the 1920s which is really cool because it teaches you math lessons you have to actually go out and physically do stuff with like pegs and strings in a field, from the perspective of the history of mathematics where people were limited to such devices in order to do stuff like trigonometry. Very very different approach, probably not for everyone, but for me I just think it's pretty cool. It definitely was written in the 1920s though so you better get used to that particular writing style if you plan on digesting it like a course. It's designed that way, though, and it's got great reviews. Just keep in mind maybe some of the history is subject to have changed over the years. [2] Ultimately I've self-taught myself a lot more than I ever learned in school for sure but a wide variety of sources is probably more what you're after in terms of getting a grip on what's interesting enough to pursue further for your own means and ends. I think exploring what fascinates you the most and then just going and finding things from that point is a pretty good start as long as you've got elementary understandings up to a point where the fascination actually happens. [1] https://www.goodreads.com/book/show/83585.Secrets_of_Mental_Math https://www.goodreads.com/book/show/83585.Secrets_of_Mental_... [2] https://www.goodreads.com/book/show/66355.Mathematics_for_the_Million https://www.goodreads.com/book/show/66355.Mathematics_for_th...