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Mathematics

Number concept, addition and subtraction

Educator section

Memorandum

1.

1.1 A: 2 613

B: 4 871

1.2 A: 2 613 = 2 000 + 600 + 10 + 3

= (2 × 1 000) + (6 × 100) + (1 × 10) + (3 × 1)

B: 4 871 = 4 000 + 800 + 70 + 1

= (4 × 1 000) + (8 × 100) + (7 × 10) + (1 × 1)

3.

3.1 800; 6

(8 × 100); (6 × 1)

3.2 4 000; 90

(4 × 1 000); (9 × 10); (8 × 1)

4.

4.1 20

4.2 8

4.3 5 000

4.4 600

BRAIN TEASERS!

a) 7 846

b) 7 740

c) 3 251

d) 8 292

e) 10

f) 100

Leaner section

Content

Activity: to recognise numbers and represent them correctly [lo 1.3]

To recognise the place value of digits [lo 1.4]

1. Every digit in every number has a certain value and meaning. Have you ever considered what the 3 in 435 819 means? Let us see.

1.1 Which number is represented in:

A: __________________________________________________________________

B: __________________________________________________________________

1.2 Write the number in expanded notation:

A: __________________________________________________________________

_____________________________________________________________________

B: __________________________________________________________________

_____________________________________________________________________

2. For the next exercise you must know the place value of every digit. If you can determine this, represent the numbers 6 038 and 4 792 on the diagrams below.

3. It is easier to recognise and represent numbers if we write them in expanded notation. By doing this we know the value of every digit. Fill in the missing numbers.

3.1 9 826 = 9 000 + ....................... + 20 + .......................

= (9 × 1 000) + (......... × .........) + (2 × 10) + (......... × .........)

3.2 4 198 = ................... + 100 + ................... + 8

= (......... × .........) + (1 × 100) + (......... × .........) + (......... × .........)

DO YOU UNDERSTAND?

The VALUE of the 7 in 8 427 is 7.

The VALUE of the 7 in 8 724 = 700.

4. Let us review the difference between value and place value. Can you tell a friend the place value of every digit below? Then write down the value of every digit in bold print.

4.1 8 329 _________________________________________________________

4.2 4 238 _________________________________________________________

4.3 25 098 _________________________________________________________

4.4 89 641 _________________________________________________________

BRAIN TEASERS!

  • See if you are able to answer the following questions correctly:

a) 7 856 is 10 more than ____________________________________________

b) 7 640 is 100 less than ____________________________________________

c) ______________________________________ is the first odd number after 3 249

d) ____________________________________ is the even number just before 8 294

e) 8 000 is ______________________________________ times bigger than 800

f) 6 000 is ______________________________________ times bigger than 60

TIME FOR SELF-ASSESSMENT

Complete the following by placing a tick in the appropriate block: Uncertain Fairly certain Altogether certain Excellent
I can count in hundreds, both forwards and backwards (LO 1.1).
I can count forwards and backwards in thousands (LO 1.1).
I know the difference between odd and even numbers (LO 1.3).
I can write numbers in expanded notation (LO 1.3).
I can determine the value of digits in numbers (LO 1.3).

Assessment

Learning Outcome 1: The learner will be able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems.

Assessment Standard 1.3: We know this when the learner recognises and represents numbers in order to describe and compare them:

Assessment Standard 1.4: We know this when the learner recognises the place value of digits in whole numbers to at least 6-digit numbers.

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Source:  OpenStax, Mathematics grade 5. OpenStax CNX. Sep 23, 2009 Download for free at http://cnx.org/content/col10994/1.3
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