ready, set, go! play this game! carry out this activity · dr fong ho kheong • chelvi...
TRANSCRIPT
Dr Fong Ho Kheong • Chelvi Ramakrishnan • Gan Kee Soon
Singapore Methodology with 100% alignment to the Indonesian
syllabus (Kurikulum 2013)
New Maths Champion is an updated edition of the successful Singapore primary maths series Maths Champion, with 100% alignment to the latest Indonesian syllabus (Kurikulum 2013). Drawing from extensive research and feedback from educators and students, this series strengthens mathematical conceptual understanding to meet the needs of educators and students.
Ready, Set, Go! introduces concepts in a format that is engaging and easy to understand, with questions that allow for immediate assessment of students’ understanding.
Carry out this activity and Play this game! develop and reinforce skills, concepts and problem-solving strategies through cooperative learning.
The direct correlation of the Workbook to the Textbook allows for thorough practice and assessment. Revisions consolidate learning and promote long-term retention of what has been learnt.
New Maths Champion comprises• Textbook•Workbook• Teacher’s Guide
© 2011 Marshall Cavendish International (Singapore) Private Limited
© 2014 Marshall Cavendish Education Pte Ltd.
This English edition is licensed to Mentari Books.
Exclusively distributed in Indonesia by:
MENTARI BOOKS
Rukan Sentra Niaga Puri Indah
Block T1 – 14, Puri Indah
West Jakarta 11610
Tel: (021) 5890 1900
: 0855 888 1948
Fax: (021) 5890 0818
E-mail: [email protected]
Website: www.mentarigroups.com
First published 2012
Second edition 2018
First reprinted 2019
All rights reserved.
© 2018, Marshall Cavendish Education Pte Ltd. This English edition licensed to
Mentari Books. All rights reserved. No part of this publication may be reproduced or
transmitted in any form or by any means, or stored in any retrieval system of any
nature without the prior written permission of Marshall Cavendish Education Pte Ltd.
New Maths Champion Textbook 4
Aligned with Indonesian syllabus (Kurikulum 2013)
Preface
is specially designed to meet the requirements of Kurikulum 2013 for Primary 1 to
Primary 6 in Indonesia. The topic coverage in each level is arranged to address all the basic
competencies (Kompetensi Dasar) of the level prescribed in the syllabus. This series uses
the Singapore approach to teaching mathematics, which is internationally recognised as
one of the best in the world.
uses Concrete-Pictorial-Abstract (CPA) approach, which is proven to be a
very effective method. The content development of each topic matches the child’s
developmental age and is carefully designed in spiral progression. Extra contents
with (*) are added to maintain this spiral progression.
gives special emphasis on the development of conceptual understanding
and creative/critical thinking skills to build a firm foundation in mathematics. After the
introduction of new concepts, students are invited to apply what they have learnt through
hands-on activities and collaborative games. The textbook offers a number of engaging
and fun activities that will stimulate students’ interest in the topic and consolidate their
knowledge and understanding.
commits to nurture young Indonesians to be efficient problem solvers who are
competent to face the changing world in the future.
Be a maths champion!
Write an improper fraction for the shaded parts.
There are 5 thirds in 123 .
123 =
13
+ 13 +
13
+ 13
+ 13
= 53
Write an improper fraction for the shaded parts.
There are quarters in 114 .
114 = + + + +
=
There are fifths in 225 .
225 =
a
b
3
2
33
, 43
, 53
and 63
are equal to or greater than 1.
They are called improper fractions.
Mr Harry has some strips of wire.
Look at Strip D. It is 113 m long.
There are 4 thirds in 113 .
113 =
13
+ 13 +
13 +
13
= 43
A
B
C
D
33 m or 1 m
13
43 m or 1 m
23m
13m
= 1 third
= 2 thirds
= 3 thirds
= 4 thirds
13
23
33
43
improper fractions
0 2
0
1
13
23
43
53
131 2
31
33
63
Ready, Set, Go!
1= 33
= 13
+ 13 +
13
Improper FractionsLesson 2
1
9392 Fractions (2) Fractions (2)Chapter 5 Chapter 5
New important mathematicalterms are emphasised.
Questions allow forimmediate assessment ofconcepts or skills learnt.
Engaging and highly scaffoldedReady, Set, Go! introduces concepts,
skills or problem solving strategies.
Using This Book
has some special features. Find out what they are for and use them to help you
learn as you use this book.
Questions allow forimmediate assessment ofconcepts or skills learnt.
The big square is divided into 100 equal parts. 25 parts are shaded.
So, 25 out of 100 parts are shaded.
25100 of the big square is shaded.
25% of the big square is shaded.
% of the big square is shaded.
% of the big square is not shaded.
Express each of the following as a percentage.
72 out of 100 is %.
39 out of 100 is %.
4
a
b
What percentage of the whole is shaded?What percentage of the whole is not shaded?
2
3
149PercentageChapter 7
Area of a triangle = 12 x base x height
In triangle PQR, QR is the base and PS is the height.
1step
Copy Figure 1 on a piece of square grid paper.
2step
Then, cut out triangles PVX and VRX.
3step
Rearrange the two triangles as shown in Figure 2.
Figure 1 Figure 2
Area of triangle PQR = area of rectangle
= 12
× area of rectangle
= 12
× QR × TR
= 12
× QR ×
= 12
× base ×
1 cm
1 cm
U T P
Q R S
VX
U T P
Q R S
V XW
Carry out this activity.
5
243Area And PerimeterChapter 12
136 DecimalsChapter 6
The players take turns to think of a decimal between 0 and 1.
Players play 2 rounds each. At each round, the players discuss
their answers.
Work in groups of three.
Thefirstplayerthinksofadecimalbetween
0 and 1. He tells the other players the decimal.
The second player says a decimal between 0 and
1thatisgreaterthanthefirstplayer’sdecimal.
The third player says a decimal between 0 and 1
thatissmallerthanthefirstplayer’sdecimal.
Returnthecardstothedeckandshuffleit.
Players take turns to play.
After playing 3 rounds each, the player with
the most number of correct answers wins.
Make a set of cards using these decimals:
Shufflethecards.
Thefirstplayerdraws3 cards. He arranges the decimals in order,
beginning with the smallest.
The other player checks his answer.
12
Play this game!
a
0.5 0.05 0.6 0.07
0.17 1.7 0.71 0.16
1.5 1.06 1.61 0.76
1step
2step
3step
4step
I can choose any decimal between 0 and 1 except 0.001 and 0.999.
Players: 2
You need: • 12 cards
b
1step
2step
3step
WB 4, p 105Practice 4B
Opportunities to enjoy maths and collaborate with friends through Play this game!
Carry out this activity offers hands-on and active learning that involves the use of
mathematics.
Thinking questions to stimulate creative and critical thinking skills during the interactive teaching-learning process.
Kompetensi Dasar
Kompetensi Dasar
3.3 Menjelaskan dan melakukan penaksiran dari jumlah, selisih, hasil kali, dan hasil bagi dua bilangan cacah maupun pecahan dan desimal
4.3 Menyelesaikan masalah penaksiran dari jumlah, selisih, hasil kali, dan hasil bagi dua bilangan cacah maupun pecahan dan desimal
3.4 Menjelaskan faktor dan kelipatan suatu bilangan
3.5 Menjelaskan bilangan prima
3.6 Menjelaskan dan menentukan faktor persekutuan, faktor persekutuan terbesar (FPB), kelipatan persekutuan, dan kelipatan persekutuan terkecil (KPK) dari dua bilangan berkaitan dengan kehidupan sehari-hari
4.4 Mengidentifikasi faktor dan kelipatan suatu bilangan
4.5 Mengidentifikasi bilangan prima
4.6 Menyelesaikan masalah yang berkaitan dengan faktor persekutuan, faktor persekutuan terbesar (FPB), kelipatan persekutuan, dan kelipatan persekutuan terkecil (KPK) dari dua bilangan berkaitan dengan kehidupan sehari-hari
Whole Numbers (1)
Factors And Multiples
Whole Numbers (2)
Lesson 1 Factors 56 Lesson 2 Multiples 59 Lesson 3 Prime Numbers 62 Lesson 4 Finding The Highest Common Factor (HCF)
By Prime Factorisation 67 Lesson 5 Finding The Lowest Common Multiple (LCM)
By Prime Factorisation 69
Lesson 1 Multiplication By A 1-Digit Number 34 Lesson 2 Multiplication By A 2-Digit Number 39 Lesson 3 Division By A 1-Digit Number 45 Lesson 4 Word Problems 50
Lesson 1 Numbers To 100 000* 10 Lesson 2 Place Value* 13 Lesson 3 Comparing Numbers Within 100 000* 17 Lesson 4 Rounding Off Numbers To The Nearest Ten 21 Lesson 5 Rounding Off Numbers To The Nearest
Hundred 26 Lesson 6 Estimation 30
Contents1Chapt rChapterChapter
3Chapt rChapterChapter
2Chapt rChapterChapter
Fractions (1)
Fractions (2)
Lesson 1 Numerator And Denominator 72 Lesson 2 Understanding Equivalent Fractions 73 Lesson 3 More Equivalent Fractions: Short Cut 76 Lesson 4 Comparing And Ordering Fractions 79
Lesson 1 Mixed Numbers 87 Lesson 2 Improper Fractions 92 Lesson 3 Conversion Of Fractions 96 Lesson 4 Fractions Of A Set 100 Lesson 5 Word Problems 104 Lesson 6 Rounding Off And Estimation Of Fractions 108
4Chapt rChapterChapter
5Chapt rChapterChapter
3.1 Menjelaskan pecahan-pecahan senilai dengan gambar dan model konkret
4.1 Mengidentifikasi pecahan-pecahan senilai dengan gambar dan model konkret
3.2 Menjelaskan berbagai bentuk pecahan (biasa, campuran, desimal, dan persen) dan hubungan di antaranya
3.3 Menjelaskan dan melakukan penaksiran dari jumlah, selisih, hasil kali, dan hasil bagi dua bilangan cacah maupun pecahan dan desimal
3.7 Menjelaskan dan melakukan pembulatan hasil pengukuran panjang dan berat ke satuan terdekat
4.2 Mengidentifikasi berbagai bentuk pecahan (biasa, campuran, desimal, dan persen) dan hubungan di antaranya
4.3 Menyelesaikan masalah penaksiran dari jumlah, selisih, hasil kali, dan hasil bagi dua bilangan cacah maupun pecahan dan desimal
4.7 Menyelesaikan masalah pembulatan hasil pengukuran panjang dan berat ke satuan terdekat
Decimals
Percentage
Lesson 1 Understanding Tenths 112 Lesson 2 Understanding Hundredths 118 Lesson 3 Understanding Thousandths 125 Lesson 4 Comparing Decimals 132 Lesson 5 Fractions And Decimals 137 Lesson 6 Rounding Off Decimals 142 Lesson 7 Rounding Off The Measurement Of Length
And Mass 147 Lesson 8 Estimation Of Decimals 149
Lesson 1 Per Cent 151
6Chapt rChapterChapter
7Chapt rChapterChapter
Kompetensi Dasar
Kompetensi Dasar
Angles
Lines And Angles
Lesson 1 Naming Angles 156 Lesson 2 Measuring Angles 157 Lesson 3 Drawing Angles To 1800 160 Lesson 4 8-point Compass* 162
Lesson 1 Perpendicular Lines 167 Lesson 2 Parallel Lines 172 Lesson 3 Angles On A Straight Line 177 Lesson 4 Angles At A Point 181 Lesson 5 Vertically Opposite Angles 185
8Chapt rChapterChapter
9Chapt rChapterChapter
3.12 Menjelaskan dan menentukan ukuran sudut pada bangun datar dalam satuan baku dengan menggunakan busur derajat
4.12 Mengukur sudut pada bangun datar dalam satuan baku dengan menggunakan busur derajat
Kompetensi Dasar
Kompetensi Dasar
Polygons Lesson 1 Polygons 190 Lesson 2 Angles Of A Triangle* 193 Lesson 3 Properties Of Quadrilaterals* 200
10Chapt rChapterChapter3.8 Menganalisis sifat-sifat segibanyak beraturan dan segibanyak tidak beraturan
4.8 Mengidentifikasi segibanyak beraturan dan segibanyak tidak beraturan
Kompetensi Dasar
3.10 Menjelaskan hubungan antar garis (sejajar, berpotongan, berhimpit) menggunakan model konkret
4.10 Mengidentifikasi hubungan antar garis (sejajar, berpotongan, berhimpit) menggunakan model konkret
145° 145°
100 110 120130
140150
160170
180
8070
60
50
40
3020
100 0
1020
30
40
50
6070
80100110
120
130
140
150
160
170
180
90100 110 120
130
140150
160170
180
8070
60
50
40
3020
100 0
1020
30
40
50
6070
80100110
120
130
140
150
160
170
180
90
A
B C
Kompetensi Dasar
Kompetensi Dasar
Bar Graphs Lesson 1 Making Bar Graphs With Scales 250 Lesson 2 Reading And Interpreting Bar Graphs 256
12Chapt rChapterChapter
11Chapt rChapterChapter
3.11 Menjelaskan data diri peserta didik dan lingkungannya yang disajikan dalam bentuk diagram batang
4.11 Mengumpulkan data diri peserta didik dan lingkungannya dan menyajikan dalam bentuk diagram batang
Area And Perimeter
Lesson 1 Square Centimetres (cm2) 210 Lesson 2 Square Metres (m2) 212 Lesson 3 Area Of A Rectangle And A Square 215 Lesson 4 Perimeter And Area 221 Lesson 5 More Area Of A Rectangle And A Square 223 Lesson 6 More Perimeter Of A Rectangle And A Square 227 Lesson 7 Base And Height Of A Triangle 230 Lesson 8 Finding The Area Of A Triangle 233 Lesson 9 Composite Figures 239 Lesson 10 Word Problems 246
3.9 Menjelaskan dan menentukan keliling dan luas persegi, persegipanjang, dan segitiga serta hubungan pangkat dua dengan akar pangkat dua
4.9 Menyelesaikan masalah berkaitan dengan keliling dan luas persegi, persegipanjang, dan segitiga termasuk melibatkan pangkat dua dengan akar pangkat dua
Glossary 260
1
10 Whole Numbers (1)Chapter 1
Whole Numbers (1)
Lesson 1
1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000,
10 thousands = 1 ten thousand
OnesTensTen
Thousands Thousands Hundreds
10 000
Let’s read the numbers. What number comes next?
10 000ten thousand
OnesTensTen
Thousands Thousands Hundreds
9000
1
Ready, Set, Go!
Lesson 1 Numbers To 100 000*
* Extra content to maintain spiral progression in the development of all related mathematical concepts, skills and knowledge.
11Whole Numbers (1)Chapter 1
Let’s read and show the numbers 15 000 and 73 486 in place value charts.
15 000fifteen thousand
OnesTensTen
Thousands Thousands Hundreds
1 5 0 0 0
73 486seventy-three thousand, four hundred and eighty-six
OnesTensTen
Thousands Thousands Hundreds
7 3 4 8 6
12 059twelve thousand and fifty-nine
What are the missing headings?
1 2 0 5 9
2
a
b
3
12 Whole Numbers (1)Chapter 1
What is the number in words?
OnesTensTen
Thousands Thousands Hundreds
5 6 8 1 7
What is the number in numerals?
OnesTensTen
Thousands Thousands Hundreds
ten thousand, two hundred and seventy-three
Let’s read the number pattern. What number comes next?
10 000, 20 000, 30 000, 40 000, 50 000, 60 000, 70 000, 80 000, 90 000,
10 ten thousands = 1 hundred thousand
100 000 one hundred thousand
What comes immediately after 99 999?
4
5
6
What is the number in words?
47 048 90 015 86 300 70 005
7
a b c d
WB 4, p 9Practice 1
You are given these play money:
Five Rp 10.000,00 Ten Rp 1.000,00 Five Rp 100,00
Use the notes given to show the amount of money.
Your friend will check you answer.Rp 24.100,00 Rp 59.400,00 Rp 37.500,00
Carry out this activity.
8
a b c
13Whole Numbers (1)Chapter 1
Place Value*
Let’s look at the number 31 798.
OnesTensTen
Thousands Thousands Hundreds
3 1 7 9 8
thirty-one thousand, seven hundred and ninety-eight
In 31 798:
the digit 3 is in the ten thousands place
the digit 3 stands for 30 thousands or 30 000the value of the digit 3 is 30 000
the digit 1 is in the thousands place
the digit 1 stands for 1 thousand or 1000the value of the digit 1 is 1000
the digit 7 is in the hundreds place
the digit 7 stands for 7 hundreds or 700the value of the digit 7 is 700
the digit 9 is in the tens place
the digit 9 stands for 9 tens or 90the value of the digit 9 is 90
the digit 8 is in the ones place
the digit 8 stands for 8 ones or 8the value of the digit 8 is 8.
Lesson 2
1
* Extra content to maintain spiral progression in the development of all related mathematical concepts, skills and knowledge.
14 Whole Numbers (1)Chapter 1
Let’s look at the number 53 827.
OnesTensTen
Thousands Thousands Hundreds
5 3 8 2 7
In 53 827:
the digit 5 is in the place
the digit 5 stands for
the value of the digit 5 is
the digit 3 is in the place
the digit 3 stands for
the value of the digit 3 is .
Find the missing numbers.
In 42 653, the digit is in the ten thousands place.
In 63 971, the digit 9 is in the place.
In 20 974, the digit in the thousands place is .
In 56 301, the value of the digit 3 is .
In 70 569, the digit 7 stands for .
In 81 465, the digit 1 stands for .
a
b
c
d
e
f
3
2
What does the digit 6 stand for in each of the following 5-digit numbers?
63 814 96 781 20 563
4
a b c
15Whole Numbers (1)Chapter 1
31 798 = 30 000 + 1000 + 700 + 90 + 8
= 31 000 + 798
Find the missing numbers.
6424 = thousands + 4 hundreds + 2 tens + 4 ones
50 328 = + 300 + 20 + 8
3 0 0 0 0
1 0 0 0
7 0 0
9 0
8
3 1 7 9 8
thirty-one thousand, seven hundred and ninety-eight
a
b
What does the digit 5 stand for in each number?
27 058 85 027 52 708
In 69 417, what is the value of each digit?
Find the missing numbers.
18 294 = 1 ten thousand + thousands + 2 hundreds + 9 tens + 4 ones
47 093 = + 7000 + 90 + 3
5
6
7
9
8
a
a
b
b c
16 Whole Numbers (1)Chapter 1
Work in groups of four.
Your teacher will give each group 10 counters and a place value chart.
The group places the counters in the place value chart to form a
5-digit number. Pupils may choose not to use all the counters given.
OnesTensTen
Thousands Thousands Hundreds
The first player writes the value of each digit in the 5-digit number
formed like this:
The group checks the answer. The first player gets 1 point if his answer is
correct.
The group rearranges the counters on the place value chart to form another
5-digit number.
Players take turns to write the values of the digits in the numbers formed.
Each player plays 3 rounds.
WB 4, p 11Practice 2
Carry out this activity.
The player with the highest score wins!
10
1step
2step
3step
4step
5step
6step
17Whole Numbers (1)Chapter 1
OnesTensTen
Thousands Thousands Hundreds
9 3 0 8 5
7 6 1 0 5
OnesTensTen
Thousands Thousands Hundreds
3 6 5 2 0
3 7 8 5 9
Which number is greater, 93 085 or 76 105?
Compare the ten thousands between the two numbers.
9 ten thousands is greater than 7 ten thousands.
So, 93 085 is greater than 76 105.
Which number is smaller, 36 520 or 37 859?
First, compare the ten thousands between the two numbers.
They are the same.
Then, compare the thousands between the two numbers.
6 thousands is smaller than 7 thousands.
So, 36 520 is smaller than 37 859.
Comparing Numbers Within 100 000*
We can compare numbers by using the place value charts to help us.
Lesson 3
1
2
Which is greater?
90 847 or 69 948 64 515 or 65 500
31 256 or 31 265 19 283 or 19 289
3
a
c
b
d
* Extra content to maintain spiral progression in the development of all related mathematical concepts, skills and knowledge.
18 Whole Numbers (1)Chapter 1
OnesTensTen
Thousands Thousands Hundreds
6 2 3 5 7
9 6 3 8
2 8 9 8 6
Which is smaller?
42 100 or 41 002 16 935 or 16 918
Arrange the numbers 62 357, 9638 and 28 986 in order.
Begin with the greatest.
Compare the ten thousands among the numbers.
So, the numbers arranged in order beginning with the greatest are:
62 357, 28 986, 9638
Arrange the following numbers in order. Begin with the smallest.
9456, 73 842, 30 512
41 325, 31 425, 51 324, 14 325
27 084, 20 784, 27 840, 20 874
2 ten thousands is greater than 0 ten thousands.
6 ten thousands is greater than 0 ten thousands and
2 ten thousands.
greatest
4
5
a b
6
a
b
c
19Whole Numbers (1)Chapter 1
Look at these two numbers: 65 123 and 67 123.
Compare the thousands between the two numbers.
65 123 is 2000 less than 67 123.
2000 more than 65 123 is .
67 123 is 2000 more than 65 123.
2000 less than 67 123 is .
Look at these two numbers: 37 625 and 7625.
30 000 more than 7625 is .
is 30 000 less than 37 625.
Find the missing numbers.
30 000 less than 34 200 is .
is 20 000 more than 53.
100 more than 58 967 is .
Find the rule for each number pattern. Then complete the number pattern.
37 642, 57 642, , 97 642
8500, , 18 500, 23 500
2985, 2885, , 2685, , 2485
24 701, 26 702, 28 703, ,
18 079, 20 079, 20 279, 22 279, 22 479, , , 26 679
OnesTensTen
Thousands Thousands Hundreds
3 7 6 2 5
7 6 2 5
OnesTensTen
Thousands Thousands Hundreds
6 5 1 2 3
6 7 1 2 3
7
8
9
10
a
a
a
b
b
b
d
c
c
e
20 Whole Numbers (1)Chapter 1
Work in groups of four.
Make four sets of number cards from 1 to 9.
Shuffle the number cards.
Take turns to draw five number cards each.
Arrange your number cards to form a 5-digit number.
Compare your 5-digit number with those formed by the other
members in your group. Then arrange the numbers in order,
beginning with the greatest.
Carry out this activity.
11
WB 4, p 13Practice 3
1step
2step
3step
4step
5step
21Whole Numbers (1)Chapter 1
Ribbon A is 82 cm long.
82 is between 80 and 90.
It is nearer to 80 than to 90.
82 is 80 when rounded off to the nearest ten.
We say 82 is approximately equal to 80.
We write 82 ≈ 80.
So, Ribbon A is 80 cm long when rounded off to
the nearest ten centimetres.
85 90
82
80
Ribbon A
Rounding Off Numbers To The Nearest Ten
Ready, Set, Go!
We use the approximation sign ≈
to stand for approximately equal to. It shows rounding off
of the numbers.
Lesson 4
1
22 Whole Numbers (1)Chapter 1
Ribbon B is 17 cm long.
17 is between 10 and 20.
It is nearer to 20 than to 10.
17 is when rounded off to the nearest ten.
17 ≈
Ribbon B is cm long when rounded off to the nearest ten centimetres.
Ribbon C is 95 cm long.
95 is exactly halfway between 90 and 100.
95 is 100 when rounded off to the nearest ten.
95 ≈ 100Ribbon C is 100 cm long when rounded off to the nearest ten centimetres.
Ribbon C
Ribbon B
17
10 15 20
95
10090 95
2
3
23Whole Numbers (1)Chapter 1
On a sheet of paper, copy the number line as shown below.
Mark each number with a cross ( ) on the number line.
Then round the number off to the nearest ten and circle it.
29 36 45 14
Round off each number to the nearest ten.
42 97 25 64
Round off 863 to the nearest ten.
863 is between 860 and 870.
It is nearer to 860 than to 870.
863 is when rounded off
to the nearest ten.
863 ≈
Round off 4156 to the nearest ten.
4156 is between 4150 and 4160.
It is nearer to 4160 than to 4150.
4156 is when rounded off
to the nearest ten.
4156 ≈
13 is 10 when rounded off to the nearest ten.
20
13
10 30 40 50
Example13
865 870860
863
4156
4155 41604150
4
5
6
7
a
a
b
b
c d
dc
24 Whole Numbers (1)Chapter 1
Round off 6455 to the nearest ten.
6455 is exactly halfway between 6450 and 6460.
6455 is when rounded off to the nearest ten.
6455 ≈
For each number, draw a number line.
Then mark the number with a cross ( ) on the number line.
Lastly, round off the number to the nearest ten and circle it.
64556450 6460
Look at each number and find the nearest ten before and after it.
Here, the number 306 lies between these two nearest tens.
So, the number line for 306 should start at 300 and end at 310.
615 4381 9098
300 306 310nearest ten before it nearest ten after it
306 is 310 when rounded off to the nearest ten.
Example306
305300
306
310
8
9
a b c
For each number, where do I start and end the number line?
25Whole Numbers (1)Chapter 1
Work in pairs.
Use number lines to help you.
Find all the numbers that give the following answers when rounded off to
the nearest ten.
(i) 50 (ii) 570 (iii) 5000
For each set of answers in a , which is
(i) the smallest number (ii) the greatest number
Find
the smallest number the greatest number
that gives 5470 when rounded off the nearest ten.
10
11
a
b
a b
Carry out this activity.
Example60
55
55 6050 65 70
56 57 58 59 61 62 63 64
55, 56, 57, 58, 59, 61, 62, 63 and 64 give the answer 60 when rounded
off to the nearest ten.
(i) 55 is the smallest number (ii) 64 is the greatest numberb
a
54705460 5480
WB 4, p 15Practice 4
26 Whole Numbers (1)Chapter 1
The volume of water in Container A is 223 ml.
223 is between 200 and 300.
It is nearer to 200 than to 300.
So, 223 is 200 when rounded off to the nearest hundred.
223 ≈ 200
The volume of water in Container A is 200 ml when rounded off to the
nearest hundred millilitres.
The volume of water in Container B is 287 ml.
287 is between and 300.It is nearer to 300 than to 200.So, 287 is 300 when rounded off to the nearest hundred.
287 ≈ 300
The volume of water in Container B is 300 ml when rounded off to the
nearest hundred millilitres.
Rounding Off Numbers To The Nearest Hundred
Container A
Container B
223
250 300200
287
250 300200
Ready, Set, Go!
Lesson 5
1
2
27Whole Numbers (1)Chapter 1
The volume of water in Container C is 650 ml.
650 is exactly halfway between 600 and 700.
So, 650 is 700 when rounded off to the nearest hundred.
650 ≈ 700
The volume of water in Container C is 700 ml when rounded off to the
nearest hundred millilitres.
Round off each of the following to the nearest hundred.
216 502 340 985
125 cm 872 kg 359 m 997 ø
Round off 2372 to the nearest hundred.
2372 is between 2300 and 2400.
It is nearer to 2400 than to 2300.
So, 2372 is 2400 when rounded off to the nearest hundred.
2372 ≈ 2400
Container C
600 650 700
2300 2350 2400
2372
3
4
5
a b c d
e f g h
28 Whole Numbers (1)Chapter 1
Round off 9632 to the nearest hundred.
9632 is between and .
9632 is nearer to than to .
9632 is when rounded off to the nearest hundred.
9632 ≈
For each number, draw a number line.
Then mark the number with a cross ( ) on the number line.
Lastly, round off the number to the nearest hundred and circle it.
Look at each number and find the nearest hundred before and after it.
Here, the number 8950 lies between these two nearest hundreds.
So, the number line for 8950 should start at 8900 and end at 9000.
516 940 5026
4158 7902 8048
8950 is 9000 when rounded off to the nearest hundred.
Example
8950
970096509600
900089508900
8900nearest hundred before it nearest hundred after it
8950 9000
6
7
a b c
d e f
29Whole Numbers (1)Chapter 1
Find all the numbers that give 2800 when rounded off to the nearest
hundred. Mark these numbers with a cross ( ) on the number line.
Which of these is the smallest number?
Which of these is the greatest number?
Find
the smallest number
the greatest number
that gives 9300 when rounded off to the nearest hundred.
9200 9300 9400
2700 2800 2900
A number when rounded off to the nearest hundred is 2800.
Round off each number to the nearest ten and hundred.
9
8
10
a
b
c
ab
WB 4, p 19Practice 5
NumberRounded off to the nearest
ten hundred
68
482
3209
7735
a
b
c
d
30 Whole Numbers (1)Chapter 1
Estimation
Estimation of sum and difference
1
First, round off each number to the nearest ten.
47 is 50 when rounded off to the nearest ten.
81 is 80 when rounded off to the nearest ten.
Then add.
50 + 80 = 130 So, 47 + 81 ≈ 130.
The value of 47 + 81 is about 130.
Estimate the value of 84 – 42.
First, round off each number to the nearest ten.
84 is 80 when rounded off to the nearest ten.
42 is 40 when rounded off to the nearest ten.
Then subtract.
80 – 40 = 40 So, 84 – 42 ≈ 40.
The value of 84 – 42 is about 40.
Let’s estimate the value of 47 + 81 to check the answer.
Ready, Set, Go!
47 ≈ 5081 ≈ 80
84 ≈ 8042 ≈ 40
1
Lesson 6
2
128 ≈ 130The answer is reasonable.
31Whole Numbers (1)Chapter 1
Round off each number to the nearest ten.
Then estimate the value of:
53 + 79 456 – 25
53 ≈ 456 ≈
79 ≈ 25 ≈
+ = – =
So, 53 + 79 ≈ . So, 456 – 25 ≈ .
Round off each number to the nearest hundred.
Then estimate the value of:
634 + 512 2426 – 1296
634 ≈ 2426 ≈
512 ≈ 1296 ≈
+ = – =
So, 634 + 512 ≈ . So, 2426 – 1296 ≈ .
The table lists the items sold at a stationery store.
Estimate the total cost of the eraser and the pencil by rounding off to
the nearest hundred.
Estimate how much more a sticker costs than a ruler by rounding off to
the nearest hundred.
3
4
5
a
a
b
b
a
b
Item Cost
Sticker Rp 850,00
Eraser Rp 920,00
Pencil Rp 890,00
Ruler Rp 610,00
32 Whole Numbers (1)Chapter 1
Estimate the value of 64 × 3.
First, round off 64 to the nearest ten.
64 is 60 when rounded off to the nearest ten.
Then multiply.
60 × 3 = 180So, 64 × 3 ≈ 180.
The value of 64 × 3 is about 180.
Estimate the value of 267 × 7.
First, round off 267 to the nearest hundred.
267 is when rounded off to the nearest hundred.
Then multiply.
× 7 =
So, 267 × 7 ≈ .
The value of 267 × 7 is about .
Estimate the value of 372 ÷ 4.
360 372 400
Then divide.
360 ÷ 4 = 90
So, 372 ÷ 4 ≈ 90.
The value of 372 ÷ 4 is about 90.
64 ≈ 60
267 ≈
372 ÷ 4
372 is nearer to 360 than to 400.
360 ÷ 4400 ÷ 4
Estimation of product and quotient
6
7
8
33Whole Numbers (1)Chapter 1
Estimate the value of 478 ÷ 8.
Then divide.
÷ 8 =
So, 478 ÷ 8 ≈ .
The value of 478 ÷ 8 is about .
Estimate the value of 559 ÷ 6.
Then divide.
÷ 6 =
So, 559 ÷ 6 ≈ .
The value of 559 ÷ 6 is about .
540 559 600
478 480
Estimate the value of 775 ÷ 8.
÷ 8 =
So, 775 ÷ 8 ≈ .
The value of 775 ÷ 8 is about .
775
559 ÷ 6
559 is nearer to 540 than to 600.
540 ÷ 6600 ÷ 6
478 is nearer to than to .
478 ÷ 8 ÷ 8
÷ 8
775 ÷ 8 ÷ 8
÷ 8
775 is nearer to than to .
9
10
11
WB 4, p 23Practice 6
Estimate the value of
395 × 6 92 ÷ 3 176 ÷ 5
12a b c