This book is great! This book teaches you tricks that really work and really makes you wonder how people came up with them.<br><br>One thing I wanted to reccommend - Although this book is for mental math, going through it, I always kept a pencil and paper by my side - some of the concepts/tricks were a little abstract to simply read and absorb the first time around, so they needed a couple of examples (on paper) to solidify the 'trick' for me. After I worked out a couple of problems on pen and paper, I was able to grasp the ability to do them mentally.<br><br>One of the best things this book teaches is guesstimation and more importantly, how to forumulate your 'guesses' so you are not so far off from target. I had been doing guesstimation for ages but the methods mentioned in the book were pretty good guidelines for my future guesses.<br><br>This book is a must have for anyone that is afraid of numbers because these simple tricks will make difficult math problems a little easier to deal with. The time saving techniques this book is filled with can shave seconds off of your problem solving skills which, come test time (math test, SAT, any test which involves math), you'll be thinking about this book and thanking the author.