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Rating: 
Summary: Truly amazing
Review: A truly amazing insight into various ways to mystify others with seemingly impossible mathematical challenges. Learn how to determine the day someone was born on, or guess the missing number in the answer to a multiplication problem. This book provides you with insight to the fun (yes... fun) side of math. You will be greatly impressed by the tricks to amaze your friends and make math interesting
Rating:
Summary: Awesome book!
Review: After seeing Dr. Benjamin perform in Las Vegas at the National Council of Teachers of Mathematics conference in 2002, I bought this book and also his Mathemagics course. My middle school students love it! Many of them prefer to do mental calculations when possible and they love when I do mathematic magic tricks on them. Better, they love the algebraic explanations and can't wait to use the tricks on their friends and family, knowing that they can explain the trick as well.
My college students are amazed when I can square a 2-digit number quicker than they can punch it in on a calculator. (I'm not too fast at the 3 digit numbers; it's hard to teach an old dog new tricks!)
I highly recommend this book for math teachers, school libraries, students, or anyone at all!
Rating: 
Summary: One path to learning mathematics
Review: Ambivalence surrounds me when I attempt to review this book. As someone who learned arithmetic in the pre-calculator days, many of the ideas in this book bring back deep memories. One of my favorite things to do when in my teen years and later was to keep track of the items in the grocery cart and estimate the total cost. It was considered a failure when the guess and true total differed by more than $0.25. While this skill did succeed in amazing people, I cannot recall a single instance where it actually was financially beneficial. And eventually I gave it up, going on to mathematics and computers.
But those days are gone, and calculators (computers) do free the mind for other things. So the question becomes, is it beneficial to read books of this type and learn the "lost" art of estimation? The history of mathematics informs us that early mental manipulation of numbers is a strong indicator of the future development of mathematical ability. Gauss and Hardy are two excellent examples of this. However, in later years Hardy in particular looked down on those who were mere number crunchers.
Which leads to the clearest use for the techniques demonstrated in this book, namely to instruct children in the mental manipulation of symbols. By having young minds compete against a calculator, mental techniques are developed that most likely cannot be created any other way. And those methods are excellent training for future careers in the quantitative sciences. And this book does an excellent job in introducing these "tricks." All are clearly explained and detailed solutions to the problems are in the back of the book. Anyone wishing to learn how to perform efficient mental computations will find what they are looking for.
If your goal is to teach or learn how to perform calculations in your head, then this book is for you. However, one should make an effort to keep everything in perspective. The ability to perform mental arithmetic should be considered as a step toward mathematical ability and not a stand-alone indicator of such skill.(Published in "Journal of Recreational Mathematics" - reprinted with permission.)
Rating:
Summary: Una pequeña joya
Review: He encontrado el libro muy útil , entretenido , y facil de leer.
Muy recomendable para iniciarse en el cálculo mental.
Rating:
Summary: Una pequeña joya
Review: He encontrado el libro muy útil , entretenido , y facil de leer.
Muy recomendable para iniciarse en el cálculo mental.
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