Tekriwal - Idiots Guides: Speed Math

No one likes a know-it-all. Most of us realize theres no such thinghow could there be? The world is far too complicated for someone to understand everything there is to know. So when you come across a know-it-all, you smile to yourself as they ramble on because you know better.

You understand that the quest for knowledge is a never-ending one, and youre okay with that. You have no desire to know everything, just the next thing. You know what you dont know, youre confident enough to admit it, and youre motivated to do something about it.

At Idiots Guides, we, too, know what we dont know, and we make it our business to find out. We find really smart people who are experts in their fields and then we roll up our sleeves and get to work, asking lots of questions and thinking long and hard about how best to pass along their knowledge to you in the easiest, most-accessible way possible.

After all, thats our promiseto make whatever you want to learn As Easy as It Gets. That means giving you a well-organized design that seamlessly and effortlessly guides you from page to page, topic to topic. It means controlling the pace youre asked to absorb new informationnot too much at once but just what you need to know right now. It means giving you a clear progression from easy to more difficult. It means giving you more instructional steps wherever necessary to really explain the details. And it means giving you fewer words and more illustrations wherever its better to show rather than tell.

So here you are, at the start of something new. The next chapter in your quest. It can be an intimidating place to be, but youve been here before and so have we. Clear your mind and turn the page. By the end of this book, you wont be a know-it-all, but your world will be a little less complicated than it was before. And well be sure your journey is as easy as it gets.

Mike Sanders
Publisher, Idiots Guides

ALPHA BOOKS

Published by Penguin Group (USA) Inc.

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Copyright 2014 by Penguin Group (USA) Inc.

All rights reserved. No part of this book may be reproduced, scanned, or distributed in any printed or electronic form without permission. Please do not participate in or encourage piracy of copyrighted materials in violation of the authors rights. Purchase only authorized editions. No patent liability is assumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of information contained herein. For information, address Alpha Books, 800 East 96th Street, Indianapolis, IN 46240.

IDIOTS GUIDES and Design are trademarks of Penguin Group (USA) Inc.

International Standard Book Number: 978-1-61564-354-7
Library of Congress Catalog Card Number: 2013945257

16 15 14 8 7 6 5 4 3 2 1

Interpretation of the printing code: The rightmost number of the first series of numbers is the year of the books printing; the rightmost number of the second series of numbers is the number of the books printing. For example, a printing code of 14-1 shows that the first printing occurred in 2014.

Printed in the United States of America

Note: This publication contains the opinions and ideas of its author. It is intended to provide helpful and informative material on the subject matter covered. It is sold with the understanding that the author and publisher are not engaged in rendering professional services in the book. If the reader requires personal assistance or advice, a competent professional should be consulted. The author and publisher specifically disclaim any responsibility for any liability, loss, or risk, personal or otherwise, which is incurred as a consequence, directly or indirectly, of the use and application of any of the contents of this book.

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Publisher:Mike Sanders

Executive Managing Editor:Billy Fields

Senior Acquisitions Editor:Tom Stevens

Development Editor:Kayla Dugger

Senior ProductionEditor/Proofreader:Janette Lynn

Cover/Book Designer:William Thomas

Indexer:Brad Herriman

Layout:Brian Massey

Introduction

Can you multiply 98 97 in your head in less than five seconds?

You may think doing such a problem in your head is a pipe dream, but its not. In fact, doing math without a calculator is critical. In places such as the United Kingdom, calculators are being banned from math tests. So if you cant do the math in your head or on a piece of paper, youre stuck.

This is where speed math comes in. By using the methods in this book, youll become more adept at solving problems, including the following:

• Addition and subtraction
• Multiplication and division
• Fractions and decimals
• Squares and square roots
• Numbers to different powers

And that doesnt cover everything youll learn. In fact, by the end of this book, youll be amazed at how quick and easy it is to solve almost any problem.

I hope you enjoy your journey into speed math.

How This Book Is Organized

This book is divided into two parts. The chapters in each part dont have to be read in order, so if you have a type of math thats of particular interest to you, feel free to skip to it.

, High-Speed Operations, provides easier ways of doing multiplication, addition, subtraction, and division. I lead off with multiplication, as it tends to have the most exciting tricks. I end this part by showing you how to check your answers using digit sums.