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Mathematics

Number concept, addition and subtraction

Educator section

Memorandum

1. 6; 12; 18; 24; 30; 36; 42; 48; 54; 60; 6; 72

7; 14; 21; 28; 35; 42; 49; 56; 63; 70; 7; 84

8; 16; 24; 32; 40; 48; 56; 64; 72; 80; 8; 96

9; 18; 27; 36; 45; 54; 63; 72; 81; 90; 9; 108

2. 72; 24; 48; 96; 108; 60

3. 1; 2; 5; 10

1; 3; 5; 15

1; 2; 4; 8; 16

1; 2; 3; 4; 6; 8; 12; 24

1; 2; 3; 5; 6; 10; 15; 30

4. 13; 2; 17; 11; 5; 23; 7; 19; 3; 29

5. 5.1

5.2 b)

6

9

4

2

1. 10 000

2. twenty six thousand four hundred and nine

3. 300

4. 5 000

5. 6; 12; 18; 24

6. 1; 2; 3; 4; 6; 12

7. true

true

TEST 1

1. 6 000 + 400 + 90 + 8

  1. × 1 000) + (4 × 100) + (9 × 10) + (8 × 1)

2. a) 200

b) 70 000

3. a) 2 674

b) 16 537

  1. 800

4. a) 7 420; 7 440

b) 16 775; 16 750

6. a)>

b)>

7. a) seventy six thousand and eight

b) 68 439

8. a) (i) 1 800

  1. 34 700

b) (i) 5 000

  1. 78 000

9 a) 6; 12; 18; 24

b) 1; 3; 17; 19

c) 1; 2; 3; 4; 6; 12

d) 2; 17; 19

e) 2; 4; 6; 12; 18; 24; 40

Leaner section

Content

Activity: to count forward in intervals [lo 1.1]

To recognise, represent, describe and compare numbers, counting down and up in fixed intervals [lo 1.3]

1. LET US RACE!

The next activity will help you to improve your skill in adding or subtracting the same number every time. This way you also learn your multiplication tables that are necessary for correct multiplication and division!

Work with a friend. You need a stopwatch. You have to "climb" the following ladders by giving the correct answers. Then it is your friend's turn. The one who works fastest while doing it CORRECTLY is the winner. (Check with a pocket calculator!)

START AT THE TOP AND GO DOWN.

NOW START AT THE BOTTOM AND GO UP.

MULTIPLES

DO YOU STILL REMEMBER?

The answers that you got in the above exercise are MULTIPLES of the 6×, 7×, 8× and 9× tables.

A MULTIPLE is obtained when a given number (e.g. 6) is multiplied by another number or series of numbers.

E.g. the multiples of 5 are 5; 10; 15; 20; 25; etc.

2. Did you know? Multiples help you to add fractions correctly. It is therefore important that you know the multiples of your multiplication tables as soon as possible. Let us practise! Colour in the multiples of 12:

FACTORS

DID YOU KNOW?

Factors are the parts/components of a multiple. Factors of 10 are: 1; 10; 2 and 5.

If we are looking for numbers that can be divided into 12, for instance, we find 1 ; 2 ; 3 ; 4 ; 6 and 12.

These numbers are FACTORS of 12.

Suggestion: Think of "pairs":

1 × 12 = 12

2 × 6 = 12

3 × 4 = 12

3. It is important to have sufficient knowledge of factors, because this can help you to divide correctly and to simplify fractions. Try to complete the table below:

Number Factors
E.g. 8 1 ; 2 ; 4 ; 8
10 ..................................................
15 ..................................................
16 ..................................................
24 ..................................................
30 ..................................................

ASK A FRIEND TO ASSESS YOUR WORK!

  • Work with a friend.
  • Answer the following questions and ask you friend to place a tick in the appropriate column:
Not at all Reason-ably good Good Excellent
I am able to recognise, describe and compare multiples (LO 1.3)
I am able to recognise, describe and compare factors (LO 1.3)
I am able to recognise, describe and compare prime numbers (LO 1.3)

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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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