Printed in China DeWALT Construction Math Quick Check: Extreme Duty Edition Christopher Prince

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2 DeWALT Construction Math Quick Check: Extreme Duty Edition Christopher Prince Vice President, Technology and Trade Professional Business Unit: Gregory L. Clayton Director of Building Trades: Taryn Zlatin McKenzie Product Development Manager: Robert Person Development: Nobina Chakraborti Director of Marketing: Beth A. Lutz Marketing Manager: Marissa Maiella Production Director: Carolyn Miller Production Manager: Andrew Crouth Content Project Manager: Brooke Greenhouse Art Director: Benjamin Gleeksman 0 Delmar, Cengage Learning All images Delmar/Cengage Learning ALL RIGHTS RESERVED. No part of this work covered by the copyright herein may be reproduced, transmitted, stored, or used in any form or by any means graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web distribution, information networks, or information storage and retrieval systems, except as permitted under Section 07 or 08 of the 976 United States Copyright Act, without the prior written permission of the publisher. For product information and technology assistance, contact us at Cengage Learning Customer & Sales Support, For permission to use material from this text or product, submit all requests online at Further permissions questions can be ed to permissionrequest@cengage.com Library of Congress Control Number: ISBN-: ISBN-0: X eisbn-0: Delmar 5 Maxwell Drive Clifton Park, NY USA Cengage Learning is a leading provider of customized learning solutions with office locations around the globe, including Singapore, the United Kingdom, Australia, Mexico, Brazil, and Japan. Locate your local office at: international.cengage.com/region Cengage Learning products are represented in Canada by Nelson Education, Ltd. Visit us at For more learning solutions, please visit our corporate website at NOTICE TO THE READER Cengage Learning and DeWALT do not warrant or guarantee any of the products described herein or perform any independent analysis in connection with any of the product information contained herein. Cengage Learning and DeWALT do not assume, and expressly disclaim, any obligation to obtain and include information other than that provided to it by the manufacturer. The reader is expressly warned to consider and adopt all safety precautions that might be indicated by the activities described herein and to avoid all potential hazards. By following the instructions contained herein, the reader willingly assumes all risks in connection with such instructions. Cengage Learning and DeWALT make no representations or warranties of any kind, including but not limited to, the warranties of fitness for particular purpose or merchantability, nor are any such representations implied with respect to the material set forth herein, and Cengage Learning and DeWALT take no responsibility with respect to such material. Cengage Learning and DeWALT shall not be liable for any special, consequential, or exemplary damages resulting, in whole or part, from the readers use of, or reliance upon, this material. DEWALT and GUARANTEED TOUGH are registered trademarks of the DEWALT Industrial Tool Co., used under license. All rights reserved. The yellow and black color scheme is a trademark for DEWALT Power Tools and Accessories. Trademark Licensee: Delmar, Cengage Learning. Executive Woods, 5 Maxwell Drive, Clifton Park, NY 065, Tel.: , A licensee of DEWALT Industrial Tools. Printed in China

3 MATH RULES Don t make costly mistakes in your math follow these simple rules. 4 5 ALWAYS USE A CALCULATOR NEVER add anything in your mind. And you should always perform each complete calculation at least twice. Once you arrive at an answer, perform the calculation again to determine if you get the same answer. If you don t, try it again. WRITE IT OUT If you don t write it down, how are you going to check it? Professionals who use math on a daily basis accountants, engineers, and the like are sometimes the most difficult students that we encounter when it comes to math. Why? Because they refuse to write it down and they will not use a calculator for what they feel is "simple math". ALWAYS MULTIPLY "LIKE NUMBERS" For example: do not multiply 0 by 4 you must either convert the 0 to inches or the 4 to feet. This is a common mistake in doing material take-offs. NEVER ROUND QUANTITIES UNTIL YOU GET TO THE END For example: if you are calculating bundles of shingles, you begin by computing squares. If you arrive at 5.4 squares, DO NOT round to 6. First multiply by the number of bundles per square. DRAW IT OUT If you have complex calculations, it always helps to get graph paper and plot it out. MATH RULES USING A SCALE

4 USING A SCALE Blueprint floor plans are typically drawn to a /4" scale to allow the builder, architect or draftsman to "scale" the drawing of the home and come up with the correct measurement. A /4" scale means that each /4" on the plan accounts for ' of actual length. If the scale is /8", it means that each /8" on the plan accounts for ' of actual length. ex. Based on a /4" inch scale, what is the actual length of a wall if the measurement on the plans is -7/6"? 4 Convert the actual measurement of the length to be "scaled" (from the plans) to its decimal equivalent..475 Extract the denominator (bottom number) from the scale specified. (If plans are drawn to a /4" scale, extract 4.) denominator is 4 Multiply the decimal equivalent of the measurement taken from the plans by the denominator of the scale..475 x 4 = This is the actual length in feet. To convert the answer to feet and inches, multiply any number to the right of the decimal place by. (The number to the left of the decimal place is "feet".) 0.75 x = 9 Actual Length is 5'9"

5 TAPE MEASURE Tape measures indicate whole numbers in inches and fractions of an inch in increments of /6. ex. What is /8 and /6 added together? Reduce the fractions to their lowest possible terms. Reduce /8 to /4; /6 will not reduce. Find the lowest common denominator for each. /4 will become 4/6 and /6 will remain the same. Add the numerators together, but keep the denominator the same. 4/6 + /6 = 7/6 /" " /4" + /6 = 7/6 /4" /8 + /6 = 7/6 5 6 /8" /6" TAPE MEASURE ROUNDING DECIMALS

6 ROUNDING DECIMALS 0.76 Rounding decimals to the nearest 00th Tenth Hundredth Thousandth 5 round second digit up < 5 second digit stays same NOTE: For construction estimating, rounding to the nearest 00th (nd decimal) is usually accurate enough for quantities such as concrete, brick, block, etc. ex. Round to the nearest 00th. Identify the hundredth place (second digit to the right of the decimal). 00th place is 9 Identify the thousandth place (third digit to the right of the decimal). 000th place is 8 If the third digit is 5 or greater, the second digit will be increased by one number. If the third digit is less than 5, the second digit (00th place) remains the same and the following digits are dropped. 000th place (the third digit) is greater than 5, so rounds up to 0.0