Essential Mathematics Book I David Rayner Oxford Essential Mathematics Book I David Rayner Oxford University Press Oxford University Press, Walton Street, Oxford OX2 6DP Oxford New York Athens Auckland Bangkok Bombay Calcutta Cape Town Dares Salaam Delhi Florence Hong Kong Istanbul Karachi Kuala Lumpur Madras Madrid Melbourne Mexico City Nairobi Paris Singapore Taipei Tokyo Toronto and associated companies in Berlin Ibadan Oxford is a trade mark of Oxford University Press © David Rayner All rights reserved. This publication may not be reproduced, stored or transmitted, in any forms or by any means, except in accordance with the terms of licences issued by the Copyright Licensing Agency, or except for fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act, 1988. Enquiries concerning reproduction outside those terms should be addressed to the Permissions Department, Oxford University Press. First published 1995 by Elmwood Press Reprinted 1996 by Oxford University Press ISBN 0 19 914661 6 Artwork by Angela Lumley Emma Djonokusumo Rachel Flowerday Lisa Lawton Lisa Lee Bidisha Bandyopadahay Fiona Lait Paulina Spencer Eleanor Galvin Typeset and illustrated by Tech-Set, Gateshead, Tyne and Wear. Printed in Great Britain by Butler & Tanner Ltd, Frome and London PREFACE This is the first of a three book series written for pupils in the age range 11-14 years. Many classrooms will contain children with a range of abilities in mathematics. This book is written to cater for this situation and also has an ample supply of questions and activities to stretch the most able. The author believes that children learn mathematics most effectively by doing mathematics. Interest and enthusiasm for the subject is engendered by working at questions which stretch the pupil forward in his or her knowledge and understanding. The author, who is a teacher, emphasises a thorough grounding in the fundamentals of number and algebra when working in the lower secondary classroom. It is hoped that the material in the books will stimulate young minds and encourage logical thinking. Some exercises provide the neces-sary practice in the basic mathematical skills required for later study. There is no set path through the book and it is anticipated that most teachers will prefer to take sections in the order of their own choice. Many activities, investigations, games and puzzles are included to provide a healthy variety of learning experiences. The author is aware of the difficulties of teaching on 'Friday afternoons' or on the last few days of term, when both pupils and teachers are tired, and suitable activities are included. The author is indebted to the many students and colleagues who have assisted him in this work. He is particularly grateful to Julie Anderson, David Moncur and Philip Cutts for their contributions to the text. The author would also like to thank Michelle Hawke for her work and sense of humour in editing and checking answers and Micheline Rayner whose encouragement to write instead of playing golf has been invaluable. David Rayner CONTENTS Page Part 1 1.1 Accurate drawing 1 1.2 Three dimensional objects : nets 9 1.3 Coordinates 12 1.4 Prime numbers, factors, multiples 26 1.5 Puzzles and games 1 31 Crossnumbers 1, Gel).eral Knowledge, Lines, Curves from straight lines. Part 2 2.1 Calculating angles 35 2.2 Decimals 45 2.3 Mixed problems 52 2.4 Area 60 2.5 Sequences 68 2.6 Puzzles and games 2 75 Puzzles, Happy numbers. Part 3 3.1 Using algebra 78 3.2 Solving equations 85 3.3 Percentages 93 3.4 Symmetry 102 3.5 Puzzles and games 3 108 Clocks, Puzzles. Part 4 4.1 Approximating 110 4.2 Using a calculator 112 4.3 Travel graphs 114 4.4 Problem solving I 120 4.5 Puzzles and games 4 124 Triangles and quadrilaterals, Crossnumbers 2, Biggest number. Part 5 5.1 Metric and Imperial units 128 5.2 Fractions 135 5.3 Charts and graphs 141 5.4 Puzzles and games 5 154 Printing a book, Diagonals, Find the hidden treasure. Part 6 6.1 Probability 156 6.2 Problem solving 2 168 6.3 Mental arithmetic 170 6.4 Puzzles and games 6 175 Puzzles, Boxes, Break the codes, Part 7 7.1 Multiple choice papers 177 7.2 Mixed exercises 182 Part 1 1.1 Accurate drawing When an architect designs a house he has to draw accurate plans for a builder to follow. In this section you will use a protractor and a pair of compasses to construct accurate diagrams involving triangles and quadrilaterals. You will also construct nets from which three dimensional shapes can be made. Measuring angles When angles are measured accurately they are usually measured in degrees. We write degrees as a number followed by the degree symbol o. A full tum = 360° A half tum = 180° A quarter tum = 90°. An angle of 90° is called a right angle. Exercise 1 In the drawings below some of the angles are correct and some are obviously wrong. State which are correct and which are wrong. You are not expected to measure the angles. p;- 4., 5.\ 6. \ 3.~ I I~~~ 2 Part 1 ; r - 7. 8. 9. 10. 11. 12. ~~2701 ~ 13. 14. 15. 16. 17. 18. ~ ~160° / ~ ~ Labelling angles The angle shown is ABC (or CBA). This angle is POR (or ROP). A p The 'B' must be in the middle. The '0' must be in the middle. Exercise 2 Write down the size of the angles stated. 1. D 2. z 3. B \ ~ A c B X (a) ABD (b) DBC (a) WXZ (b) ZXY (a) B~C (b) ACB (c) CBA Accurate drawing 3 K 6. D c F L A (a) DEF (a) KLM (a) DCB (b) DFE (b) KML (b) ABD (c) FDE (c) NM:K (c) COB Using a protractor The protractor is one of the most commonly misused of mathematical instruments. It is important to read the answer from the correct scale. Remember: When measuring an acute angle the answer must be less than 90°. When measuring an obtuse angle the answer must be more than 90°. Exercise 3 Copy and complete the table. Q p \ HI ~" "' <§l ~ G'---......_ -B --A (a) AQD = 20° AON= AOL = 60° AOK= (b) ZOF = ZOP = ZOR = ZOT = (c) ZQI = ZOG = AOC= AOV = (d) AOQ = AQP = AOF = AOB = (e) ZOH = ZOB = zoe= ZOD = (f) AOG = AOH= AOI AOM= (g) AOR = ZOE = 155° ZOJ = ZOK =
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