This seems to be the kind of this you are looking for.
Hi, this may be the wrong forum, but is there any math books that allow one to get better at advance mental math? IE how to square 91. You know the +/- 9 to get 100 and 82. Then 82 * 100 + 9^2 to get the answer of 8281. How to do math like that but easier or simpler because it is pretty complex to carry over numbers in your head.
Thanks, craig! I hadn't heard of that but it is fascinating.
Barthayn, if you just do a quick Google search for "mental calculation tricks" you will find a lot of cool stuff. This is the Wikipedia page on it:
Also, if you check out this book on Amazon you will find a lot of related books as well:
Coincidentally, I just bought this book, though I have not started it yet. Good luck!