Math for Grownups: Relearn the Arithmetic You Forgot from School

277 Pages·2011·1.8 MB·English

by  Laura Laing

MATH
FOR
GROWNUPS

Relearn the Arithmetic You
Forgot from School So You Can:

Calculate how much that raise will
really amount to (after taxes)
Figure out if that new fridge will actually fit Help a third grader with his
fraction homework Convert calories into cardio time
LAURA LAING
BS, Math Educator
Copyright © 2011 by F+W Media, Inc.
All rights reserved.
This book, or parts thereof, may not be reproduced in any
form without permission from the publisher; exceptions are
made for brief excerpts used in published reviews.
Published by
Adams Media, a division of F+W Media, Inc.
57 Littlefield Street, Avon, MA 02322. U.S.A.
www.adamsmedia.com
ISBN 10: 1-4405-1263-9
ISBN 13: 978-1-4405-1263-6
eISBN 10: 1-4405-2689-3
eISBN 13: 978-1-4405-2689-3
Printed in the United States of America.
10 9 8 7 6 5 4 3 2 1
Library of Congress Cataloging-in-Publication Data
Laing, Laura.
Math for grownups / Laura Laing.
p. cm.
Includes index.
ISBN 978-1-4405-1263-6
1. Mathematics-Popular works. I. Title.
QA93.L27 2011
510-dc22
2011010369
This publication is designed to provide accurate and authoritative
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—From a Declaration of Principles jointly adopted by a Committee of the
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Dedication

For my three favorite mathematicians:
Dad, Gina, and Zoe.
Contents
INTRODUCTION:
Everyday Math: Easier Than Running Out of Paint
1 AT THE STORE:
Deal or No Deal?
2 AT THE DEALERSHIP:
Leasing vs. Buying, New vs. Used—You Do the Math
3 ON THE MARKET:
Buying a House by the Numbers
4 AT HOME:
Will Your New Fridge Fit?
5 IN THE KITCHEN:
Making More, Making Less—Recipe
Math to the Rescue!
6 IN THE YARD:
If a Train Leaves Omaha at 8 A.M.,
How Much Lawn Edging Do You Need?
7 IN THE CRAFT ROOM:
Measure Twice, Cut Once
8 AT THE BANK:
Income Minus Expenses Equals Happiness (or Misery)
9 IN THE GYM:
How Many Miles on the Treadmill to
Burn Off One Doughnut?
10 ON THE ROAD:
When Will You Get There and
How Much Will You Spend?
APPENDIX: Fabulous Formulas
Glossary
Index
Introduction
Everyday Math: Easier Than Running Out of Paint

The numbers game plays a starring role in almost every part of daily life,
from making dinner to planning a weekend getaway. Heck, you need math to
order a pizza.
Even people who don’t sweat math problems—namely, mathematicians!—
sometimes have trouble with the calculations we face in everyday life. So it’s no
wonder that those of us who have already forgotten what we learned in high
school (or, worse, never liked math and didn’t do well in it) can sometimes stare
at a math problem and not have the faintest idea what to do about it.
But luckily you don’t have to be Stephen Hawking (or even be proficient with
a scientific calculator) to use math in ordinary situations. Remember, it’s only a
tool. (And it’s not even one that requires safety glasses or special training so you
won’t cut off the tip of your left index finger.) It’s a language that describes how
our world fits together. Math enables us to make predictions and quick decisions.
Math helps us feel powerful and confident.
Here’s the honest truth: Adding fractions is no harder than signing up for the
office football pool or buying airline tickets online or remembering how to
create a folder on your computer desktop. It may just seem more challenging.
The truth is that very few people in the world can’t do math. You are not one
of them. Here’s the thing—most math doesn’t require you to remember how to
find the slope of a line (or even to remember what slope is). The everyday stuff
is a combination of basic arithmetic and your innate understanding of how to
speak the language of numbers, shapes, and measurements.
Yep, innate. You were born with curiosity about the world around you. Math
is just one way to describe that world. And, like it or not, it’s a pretty important
way.
So unless you don’t care what’s in your bank account or whether your new
elliptical machine will fit through the door of your exercise room, you’re going
to have to do some math.
And you might as well think you’re good at it, right? (Because, guess what?
You are.)
You don’t have to know calculus to figure out how to lower your monthly
mortgage payments. You don’t have to remember the Pythagorean Theorem to
lose a few extra pounds. And you don’t have to do long division in your head to
buy paint for your new house.
You do need to have an open mind and a sense of humor. After all, it’s only
math.