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BCRB295038 ISBN 978-616-541-319-0
9 786165 413190
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©Pelangi Publishing (Thailand) Co., Ltd. 2019 All rights reserved. No part of this publication may be reproduced, stored in any retrieval system or transmitted in any form or by any means without permission of Pelangi Publishing (Thailand) Co., Ltd. 2019
BCRB295038 PESPMathematicsP5TB_Titlepage.indd 1
ISBN 978-616-541-319-0 First Published 2562
31/1/2562 BE 16:00
Contents Chapter 1 Whole numbers
C Estimating the results of decimal addition and subtraction....................... 49
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D Multiplication of decimals..................... 53
A Combined operations........................... 2 B Solving word problems involving combined operations............................ 5
Chapter 2 Fractions
E
Division of decimals.............................. 60
F
Solving word problems involving multiplication and division of decimals............................................... 67
G Performing combined operations on decimals.......................................... 69
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H Solving word problems involving combined operations on decimals........ 71
A Comparing fractions............................. 12 B Addition and subtraction of fractions.... 15
Chapter 4
C Multiplication of fractions...................... 19 D Division of fractions.............................. 25
Percentage
76
E
Combined operations of fractions......... 31
A Reading and writing percentages......... 77
F
Solving word problems involving combined operations of fractions......... 34
B Finding the percentages of whole numbers............................................... 81
Chapter 3 Decimals
C Writing a discount as a percentage...... 83 D Solving word problems involving percentages.......................................... 86
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A Relationship between fractions and decimals........................................ 40 B Estimating decimals............................. 45
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Chapter 5 Length
Chapter 9
90
Quadrilaterals
138
A Relationships between units of length.................................................... 91
A Types and properties of quadrilaterals........................................ 139
B Measuring length.................................. 94
B Diagonals of quadrilaterals................... 142
C Solving word problems involving length.................................................... 99
C Constructing quadrilaterals................... 146
Chapter 6
E
Area of a quadrilateral.......................... 154
F
Solving word problems involving quadrilaterals........................................ 157
Mass
D Perimeter of a quadrilateral.................. 151
102
A Relationships between units of mass..................................................... 103 B Measuring mass................................... 105
Chapter 10
C Solving word problems involving mass..................................................... 108
A Characteristics of prisms...................... 163
Chapter 7
Volume and capacity
Prisms
Chapter 11 Data presentation
111
B Relationships between units of volume and capacity............................. 116
B Reading and drawing multiple bar charts.................................................... 173
C Solving word problems involving volumes and capacities of cuboids....... 118
Lines and angles
167
A Reading and drawing bar charts with a jagged line.................................. 168
A Volume and capacity of a cuboid.......... 112
Chapter 8
162
C Reading line graphs............................. 178
121
A Corresponding, alternate, interior and exterior angles...................................... 122 B Perpendicular lines............................... 128 C Parallel lines......................................... 129 D Drawing parallel lines........................... 131
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Special features in this book
Provides practical activities to enhance students’ interest, knowledge and experience in learning mathematics.
Encourages students to recall and list down what they know about the topic.
Provides an activity that engages in the application of knowledge of scientists, mathematicians and engineers.
Provides the learning outcomes of the lesson and encourages students to share what they want to learn in the topic.
Challenges students with questions that promote higher thinking skills.
4C’s of the 21st Century 4C’s The Skills are Communication Sharing thoughts, questions, ideas and solutions.
Helps students to identify what they have learned at the end of the lesson.
Collaboration Working together to reach a goal. Putting talent, expertise and smarts to work. Provides exercises to reinforce students’ grasp of mathematical concepts.
Critical Thinking Looking at problems in a new way and linking learning across subjects and disciplines. Creativity Trying new approaches to get things done equals innovation and invention.
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1
Chapter
Whole numbers A farm produces 21,246 tomatoes. 1,576 of the tomatoes are rotten. The remaining tomatoes are packed into boxes of 35. How many boxes of tomatoes will there be?
What do I know about whole numbers? 1. 2. 3. What else do I want to know about whole numbers? 1. How do I find answers to combined operations? 2. How do I solve word problems involving combined operations? 3.
A Combined operations Whole numbers are positive numbers, including zero, without any decimal or fraction. For example, 3, 254, 1,078 and 61,230 are all whole numbers.
When performing combined operations, always work from the left to the right, do the multiplication or division before doing the addition or subtraction. If there are brackets, always do the operations within the brackets first, followed by multiplications and divisions, and finally additions and subtractions.
325 + 416 × 20 ÷ 16 – 777 = Working: 325 + 416 × 20 ÷ 16 – 777
= 325 + 416 × 20 ÷ 16 – 777
= 325 + 8,320 ÷ 16 – 777
= 325 + 520 – 777
= 845 – 777
= 68 Answer:
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325 + 416 × 20 ÷ 16 – 777 = 68
MATHEMATICS Prathomsuksa
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Do the multiplication or division first before the addition or subtraction. Work from left to right.
Work from left to right.
1,250 × 30 ÷ (30,149,870 – 30,149,855) = Working: 1,250 × 30 ÷ (30,149,870 – 30,149,855) = 1,250 × 30 ÷ (30,149,870 – 30,149,855) = 1,250 × 30 ÷ 15 = 37,500 ÷ 15
Do the operation in the brackets first.
Work from left to right.
= 2,500 Answer: 1,250 × 30 ÷ (30,149,870 – 30,149,855) = 2,500 (25,348 + 2,132) ÷ 30 × 24 – 13,125 = Working: (25,348 + 2,132) ÷ 30 × 24 – 13,125
Do the operation in the brackets first.
= (25,348 + 2,132) ÷ 30 × 24 – 13,125 = 27,480 ÷ 30 × 24 – 13,125 = 916 × 24 – 13,125
Work from left to right.
= 21,984 – 13,125 = 8,859 Answer: (25,348 + 2,132) ÷ 30 × 24 – 13,125 = 8,859 374 × 46 – 3,126 + 14,950 ÷ 65 = Working: 374 × 46 – 3,126 + 14,950 ÷ 65 = 374 × 46 – 3,126 + 14,950 ÷ 65
Do the multiplication and division first before the addition or subtraction.
= 17,204 – 3,126 + 14,950 ÷ 65 = 17,204 – 3,126 + 230 = 14,078 + 230
Work from left to right.
= 14,308 Answer: 374 × 46 – 3,126 + 14,950 ÷ 65 = 14,308
Whole numbers
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Find the answers. 1. 11,232 ÷ (6 × 8) + 48,178 = Working:
Answer: 2. 2,365 + 678 × 200 ÷ 25 = Working:
Answer: 3. (23,852 – 12,450) × 16 + 96,450 ÷ 25 = Working:
Answer: 4. 185 × 26 + (25,678 – 12,442) ÷ 12 = Working:
Answer: 5. 1,120 – 50 × 8 ÷ 2 + 520 = Working:
Answer:
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MATHEMATICS Prathomsuksa
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B
Solving word problems involving combined operations
A trader buys 280 wallets and 95 handbags for 351,970 Baht. If the wallets cost 495 Baht each, what is the cost of each handbag? Analyzing the problem: What do you know? ✰ Number of wallets = 280 ✰ Number of handbags = 95 ✰ Total cost = 351,970 Baht ✰ Cost of each wallet = 495 Baht
What do you need to find out? ✰ The cost of each handbag
What operations do you use? ✰ Multiplication, subtraction and division
Working: (351,970 – 280 × 495) ÷ 95 = The number of wallets bought:
280
The cost of a wallet:
495
Total cost of wallets:
138,600
Total cost of wallets and handbags:
351,970
Total cost of wallets:
138,600
Total cost of handbags:
213,370
The number of handbags bought:
×
–
Baht
Baht Baht Baht
95
The cost of each handbag is 213,370 ÷ 95 = 2,246 Baht. Answer: The cost of each handbag is 2,246 Baht.
Whole numbers
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A pupil can type 120 words in 90 seconds. How many words could be typed in 360 seconds? Working: In 90 seconds, the pupil can type In 1 second, the pupil can type
120 words. 120 ÷ 90 =
In 360 seconds, the pupil can type 360 ×
120 words. 90
120 = 480 words. 90
Answer: The pupil can type 480 words in 360 seconds. A worker earns 8,500 Baht in 10 days. How much will he earn in 65 days?
Working: In 10 days, the worker earns
8,500 Baht.
In 1 day, the worker earns
8,500 ÷ 10 = 850 Baht.
In 65 days, the worker earns
65 × 850 = 55,250 Baht.
Answer: The worker earns 55,250 Baht in 65 days.
The price of 15 kg of rice is 570 Baht. What is the price of 45 kg of rice? Working: The price of 15 kg of rice is
570 Baht.
The price of 1 kg of rice is
570 ÷ 15 = 38 Baht.
The price of 45 kg of rice is 45 × 38 = 1,710 Baht. Answer: The price of 45 kg of rice is 1,710 Baht.
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MATHEMATICS Prathomsuksa
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1. A farm produces 19,500 eggs a day. The eggs are arranged on trays
with 30 eggs each. Each tray of eggs is sold at 105 Baht. How much money does the farm make in a day?
Working:
Answer: 2. Jess has 82,635 Baht. She buys 76 T-shirts at 195 Baht each and 94 pairs of pants at 425 Baht each. How much money does Jess have left? Working:
Answer:
Whole numbers
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3. Sam drove his car 24 km with 2 liters of petrol. How many kilometers can Sam drive with 15 liters of petrol?
Working:
Answer: 4. 30 oranges cost 210 Baht. How much do you need to pay to buy 55 oranges?
Working:
Answer: 5. If Cindy sells 4 kg of flour for 76 Baht, how much money will she get by selling 18 kg of flour?
Working:
Answer: What have I learned about whole numbers? I have learned how to find answers to combined operations.
solve word problems involving combined operations.
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MATHEMATICS Prathomsuksa
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Transportation game Bangkok is currently served by three rail rapid transit systems, namely MRT, BTS and ARL. In 2020, Bangkok will have many more public transportation lines which are interconnected. Your challenge: You and your team are required to come up with a game for 2 players. It is about traveling on the rail rapid transit systems in Bangkok. You should set the rules so that the winner is the first person to travel through or change trains at every station on the system. Write a complete set of instructions for the game. You can put extra details on the board or map if you wish. Points to ponder: You should think about: – Who plays (age, gender)?
– Objectives of the game – What is it all about? – Rules (How to start, how to make a move, the price of the ticket) – Set up the ticket prices so that you can calculate the cost of the trip. Suggested materials: Cardboard Map Dice Token ASK
IMAGINE
What do you know? What do you need to know to get started?
What are your possible solutions? Brainstorm solutions. Choose the best one.
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PLAN
Draw your design. List the materials that you need.
CREATE
Follow your plan and create your solution. Test it.
IMPROVE
What works? What does not work? How will you modify your solution to make it better? Test it again.
PRESENT
Prepare a presentation and share it with your class.
MATHEMATICS Prathomsuksa
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BCRB295038 ISBN 978-616-541-319-0
9 786165 413190
5