Editors of Portable Press - See Ya Later Calculator

SIMPLE MATH TRICKS
YOU CAN DO IN YOUR HEAD Copyright 2017 Portable Press All rights reserved. No part of this publication may be reproduced,
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addressed to Portable Press, Editorial Department, at the above address. Publisher: Peter Norton
Publishing/Editorial Team: Vicki Jaeger, Tanya Fijalkowski,
Lauren Taniguchi, Aaron Guzman
Editorial Team: JoAnn Padgett, Melinda Allman, J.

Carroll, Dan Mansfield
Production Team: Jonathan Lopes, Rusty von Dyl Cover design by Tom Deja
Illustrations by Ana Djordjevic and Rusty von Dyl
Interior design by Trina Janssen and Lidija Tomas eBook ISBN: 978-1-62686-812-0 eBook Edition: May 2017 CONTENTS Math shouldnt be a four-letter word! Its useful, astounding, and even (gulp!) fun, yet four in ten Americans still claim they hate the subject. We figured that if we compiled the niftiest tricks, games, and do-it-yourself projects, we could help solve peoples irrational fear of math. From tips you can use in everyday life to special occasion algebra and geometry, See Ya Later Calculator has everything you need to master this radical subject. With these easy shortcuts, even our most numerically challenged readers will be able to do math in their head. Plus, the Pen + Paper Math section has bonus problems that are too hard to do mentallyunless youre a math genius (in which case, you should write our next book!). Our math moguls, whose input was integral:

J. Carroll	JoAnn Padgett
Tom Deja	Megan Todd
Ana Djordjevic	Anna Nguyen
Trina Janssen	Alex Firer
Rusty von Dyl	Jay Newman
Lidija Tomas	Tracy Vonder Brink
Brian Boone	Adam Bolivar
Dan Mansfield	Tanya Fijalkowski
Vicki Jaeger	Lilian Nordland
Melinda Allman	Meighen Severance

Arithmetic is being able to count up to twenty without taking off your shoes. Mickey Mouse PRE-DETERMINE YOUR GROCERY STORE TOTALYoure at the grocery store. Youre on a budget, or the store takes cash only. That means youre watching almost every centyoull need to estimate as you go. Say youve come to the store to purchase exactly seven things: bread, eggs, milk, carrots, peanut butter, cereal, and a banana.

Youve got $20. Because you dont have a calculator or paper with you (youve got your list memorized!), youll have to remember the prices along the way. The trick is to guesstimate (thats guess + estimate) the prices by rounding up or down. If you do it to the nearest 50 cents (meaning if something is $0.20, round it down to 0; if something is $2.45, round up to $2.50), youll be very close to the actual figure at the endand within your budget. Plus the numbers will be easy to remember as you work your way down your list.

Item	Actual cost	Guesstimated cost
Bread	$0.79	$1.00
Eggs	$2.29	$2.50
Milk	$3.89	$4.00
Carrots	$1.99	$2.00
Peanut butter	$3.09	$3.00
Cereal	$3.39	$3.50
Banana	$0.29	$0.50
$15.73	$16.50

Nice going! Your guesstimate was just 77 cents from the total, and well within your spending limit.

That means you can buy everything on your listas well as pay the sales tax. SIMPLIFIED SUBTRACTIONIf two-digit subtraction is hard, its because things arent simplified far enough. Heres a way to make it way simpler, way earlier. The key is to break the numbers into manageable chunks. Take the bottom number and round it down to a decade number and its remainder.