Zusatztext A great introduction to the wonder of numbers! from two superb teachers. Brian Greene! author of The Elegant Universe A magical mystery tour of mental mathematics! Fascinating and fun. Joseph Gallian! president of the Mathematical Association of America The clearest! simplest! most entertaining! and best book yet on the art of calculating in your head. Martin Gardner! author of Mathematical Magic Show and Mathematical Carnival This book can teach you mental math skills that will surprise you and your friends. Better! you will have fun and have valuable practical tools inside your head. Dr. Edward O. Thorp! mathematician and author of Beat the Deale r and Beat the Market Informationen zum Autor Arthur Benjamin is a professor of mathematics at Harvey Mudd College in Claremont, California. He is also a professional magician and performs his mixture of math and magic all over the world. Michael Shermer is host of the Caltech public lecture series, a contributing editor to and monthly columnist of Scientific American , the publisher of Skeptic magazine, and the author of several science books. He lives in Altadena, California. Klappentext These simple math secrets and tricks will forever change how you look at the world of numbers. Secrets of Mental Math will have you thinking like a math genius in no time. Get ready to amaze your friends-and yourself-with incredible calculations you never thought you could master, as renowned "mathemagician" Arthur Benjamin shares his techniques for lightning-quick calculations and amazing number tricks. This book will teach you to do math in your head faster than you ever thought possible, dramatically improve your memory for numbers, and-maybe for the first time-make mathematics fun. Yes, even you can learn to do seemingly complex equations in your head; all you need to learn are a few tricks. You'll be able to quickly multiply and divide triple digits, compute with fractions, and determine squares, cubes, and roots without blinking an eye. No matter what your age or current math ability, Secrets of Mental Math will allow you to perform fantastic feats of the mind effortlessly. This is the math they never taught you in school.Chapter 0 Quick Tricks: Easy (and Impressive) Calculations In the pages that follow, you will learn to do math in your head faster than you ever thought possible. After practicing the methods in this book for just a little while, your ability to work with numbers will increase dramatically. With even more practice, you will be able to perform many calculations faster than someone using a calculator. But in this chapter, my goal is to teach you some easy yet impressive calculations you can learn to do immediately. We'll save some of the more serious stuff for later. Instant Multiplication Let's begin with one of my favorite feats of mental mathhow to multiply, in your head, any two-digit number by eleven. It's very easy once you know the secret. Consider the problem: 32 3 11 To solve this problem, simply add the digits, 3 1 2 5 5}, put the 5 between the 3 and the 2, and there is your answer: 35}2 What could be easier? Now you try: 53 3 11 Since 5 1 3 5 8, your answer is simply 583 One more. Without looking at the answer or writing anything down, what is 81 3 11? Did you get 891? Congratulations! Now before you get too excited, I have shown you only half of what you need to know. Suppose the problem is 85 3 11 Although 8 1 5 5 1}3}, the answer is NOT 81}3}5! As before, the 3} goes in between the numbers, but the 1} needs to be added to the 8...

ldquo;A great introduction to the wonder of numbers, from two superb teachers.”
—Brian Greene, author of The Elegant Universe

“A magical mystery tour of mental mathematics! Fascinating and fun.”
—Joseph Gallian, president of the Mathematical Association of America

“The clearest, simplest, most entertaining, and best book yet on the art of calculating in your head.”
—Martin Gardner, author of Mathematical Magic Show and Mathematical Carnival

“This book can teach you mental math skills that will surprise you and your friends. Better, you will have fun and have valuable practical tools inside your head.”
—Dr. Edward O. Thorp, mathematician and author of Beat the Dealer and Beat the Market

Autorentext
Arthur Benjamin is a professor of mathematics at Harvey Mudd College in Claremont, California. He is also a professional magician and performs his mixture of math and magic all over the world.

Michael Shermer is host of the Caltech public lecture series, a contributing editor to and monthly columnist of Scientific American, the publisher of Skeptic magazine, and the author of several science books. He lives in Altadena, California.

Klappentext

These simple math secrets and tricks will forever change how you look at the world of numbers.

Secrets of Mental Math will have you thinking like a math genius in no time. Get ready to amaze your friends-and yourself-with incredible calculations you never thought you could master, as renowned "mathemagician" Arthur Benjamin shares his techniques for lightning-quick calculations and amazing number tricks. This book will teach you to do math in your head faster than you ever thought possible, dramatically improve your memory for numbers, and-maybe for the first time-make mathematics fun.

Yes, even you can learn to do seemingly complex equations in your head; all you need to learn are a few tricks. You'll be able to quickly multiply and divide triple digits, compute with fractions, and determine squares, cubes, and roots without blinking an eye. No matter what your age or current math ability, Secrets of Mental Math will allow you to perform fantastic feats of the mind effortlessly. This is the math they never taught you in school.

Leseprobe
Chapter 0

Quick Tricks: Easy (and Impressive) Calculations

In the pages that follow, you will learn to do math in your head faster than you ever thought possible. After practicing the methods in this book for just a little while, your ability to work with numbers will increase dramatically. With even more practice, you will be able to perform many calculations faster than someone using a calculator. But in this chapter, my goal is to teach you some easy yet impressive calculations you can learn to do immediately. We’ll save some of the more serious stuff for later.

Instant Multiplication

Let’s begin with one of my favorite feats of mental math—how to multiply, in your head, any two-digit number by eleven. It’s very easy once you know the secret. Consider the problem:

32 3 11

To solve this problem, simply add the digits, 3 1 2 5 5}, put the 5 between the 3 and the 2, and there is your answer:

35}2

What could be easier? Now you try:

53 3 11

Since 5 1 3 5 8, your answer is simply

583

One more. Without looking at the answer or writing anything down, what is

81 3 11?

Did you get 891? Congratulations!

Now before you get too excited, I have shown you only half of what you need to know. Suppose the problem is

85 3 11

Although 8 1 5 5 1}3}, the answer is NOT 81}3}5!

As before, the 3} goes in between the numbers, but the 1} needs to be added to the 8 to get the correct answer:

93}5

Think of the problem this way:

Here is another example. Try 57 3 11.

Since 5 1 7 5 12, the answer is

Okay, now it’s your turn. As fast as you can, what is

77 3 11?

If you got the answer 847, then give yourself a pat on the back. You are on your way to becoming a mathemagician.

Now, I know from experience that if you tell a friend or teacher that you can multiply, in your head, any two-digit number by eleven, it won’t b…