R SachidanandanConsultant

Dr Spario Soon

TEXTBOOK 5A5A

•APPROVED

BYMINISTRY OF EDU

CATION

•

for use from 2008–2

016

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Preface

Explore Maths is a series of textbooks and accompanying workbooks specially written to meet the mathematical needs of primary school pupils.

This series adopts a learner-centred and lively approach to teaching Mathematics.

Each chapter in the textbook begins with a warm-up section which creates an opportunity for class discussion and interaction. Numerous illustrations in each chapter enhance pupils’ understanding of the mathematical concepts. Stimulating questions and fun activities challenge pupils to think critically and creatively.

Through Explore Maths, pupils can become proficient in Mathematics while learning to appreciate the beauty and power of the subject.

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About The Book

Each chapter in the Explore Maths textbook has the following features:

You will learn toHighlights the learning outcomes of the chapter.

Warm-UpCreates an opportunity for class discussion and interactions.

Directs pupils to the appropriate worksheet.

Work It OutActs as a quick review.

Indicates the use of calculator in the book.

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Let’s See In Everyday LifeRelates what’s taught to daily scenarios.

Stop-Think-GoEncourages pupils to think further.

EnrichmentEngages pupils with fun-filled activities that promote critical and creative thinking skills.

Self-testA quick assessment of pupils’ understanding of the chapter.

Types of activities found in ‘Enrichment’:

: Pair/Group activity

: Problem Solving activity

: IT activity

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CHAPTER 1 Numbers up to 10 000 000 1

A Counting 2 B Comparing and ordering 13 C Rounding off 17

CHAPTER 2 The four operations 23

A Adding numbers 24 B Subtracting numbers 31 C Adding and subtracting mentally 38 D Multiplication 40 E Division 57 F Order of operations 71

CHAPTER 3 Word problems 77

A 1-step word problems 78 B 2-step and 3-step word problems 80

CHAPTER 4 Factors and multiples 87

A Factors 88 B Common factors 92 C Multiples 94 D Common multiples 96

Contents

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CHAPTER 5 Fractions and mixed numbers 99

A Numerator and denominator 100 B Equivalent fractions 102 C Fraction in its simplest form 106 D Comparing and ordering fractions 107 E Mixed numbers 112 F Improper fractions 113 G Expressing mixed numbers as improper

fractions 115 H Expressing improper fractions as mixed

numbers or whole numbers 117

CHAPTER 6 Angles 121

A Naming, estimating and measuring angles 122 B Finding angles 127 C Drawing angles 132

CHAPTER 7 Perpendicular and parallel lines 135

A Horizontal lines and vertical lines 136 B Parallel lines 140

CHAPTER 8 Rectangles and squares 145

A Rectangles 146 B Squares 149 C Drawing rectangles and squares 151

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Explore Maths 1

They are 7-digit numbers. How do I read these numbers?

In this chapter, you will learn to:

• read and write numbers up to 10 000 000;• recognise the place values of millions, hundred thousands,

ten thousands, thousands, hundreds, tens and ones;• compare and order numbers up to 100 000;• round off numbers to the nearest 10, 100 and 1000.

Look at the table below. What do you notice about the numbers?

For example, look at the population of Brisbane. The digit 2 is followed by 6 zeros. We read this number as 2 million. Try reading the other numbers.

City/Country Estimated population in year 2008

Brisbane About 2 000 000

Singapore About 5 000 000

New Zealand About 4 000 000

Hong Kong About 8 000 000

Numbers up to 10 000 0001

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2 Numbers up to 10 000 000

Numbers and place values

10, 20, 30, 40, … (Count on by tens.)

What number is 10 more than 90?

100, 200, 300, 400, … (Count on by hundreds.)

What number is 100 more than 900?

1000, 2000, 3000, 4000, … (Count on by thousands.)

What number is 1000 more than 9000?

10 000, 20 000, 30 000, 40 000, … (Count on by ten thousands.)

What number is 10 000 more than 90 000?

Look at the bead counter below.

The number 3567 has 4 digits, 3, 5, 6 and 7. The value of each digit depends on the position it occupies in the number.

A Counting

Thousands Hundreds Tens Ones

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Explore Maths 3

We can put the digits, 3, 5, 6 and 7 in a place value chart.

The digit 3 is in the thousands place. It stands for 3000.The digit 5 is in the hundreds place. It stands for 500.The digit 6 is in the tens place. It stands for 60.The digit 7 is in the ones place. It stands for 7. 3567 = 3000 + 500 + 60 + 7

3567 is written as three thousand, five hundred and sixty-seven in words.

What is 1000 more than 3567?

1000 more than 3567 is .

Add 1000.

Thousands Hundreds Tens Ones

3 5 6 7

Thousands Hundreds Tens Ones

3 5 6 7

1 0 0 0

? ? ? ?

Add 1000.

Thousands Hundreds Tens Ones

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4 Numbers up to 10 000 000

Ten Thousands

Thousands Hundreds Tens Ones

6 7 2 8 4

The number 67 284 has 6 ten thousands, 7 thousands, 2 hundreds, 8 tens and 4 ones.

6 ten thousands = 60 000 7 thousands = 7000 2 hundreds = 200 8 tens = 80 4 ones = 4

67 284 = 60 000 + 7000 + 200 + 80 + 4 = 67 000 + 200 + 80 + 4

67 284 is written as sixty-seven thousand, two hundred and eighty-four in words.

Thousands Hundreds Tens OnesTen

Thousands

sixty-seven thousand

two hundred

eighty

four

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