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1.1 24; 48; 64; 32; 120; 16; 96; 88
1.2 36; 18; 45; 81; 54; 63; 108;
1.3 36; 24; 48; 144; 60; 120; 96; 108;
2.1 27
2.2 68,5
2.3 10
2.4 6
2.5 +
2.6 54
2.7 7
2.8 300
2.9 300
2.10 984
2.11 8
2.12 43
2.13 112
2.14 72
2.15 134
2.16 4
2.17 132
2.18 84
2.19 3 600
2.20 7 000
3.1 10 000
3.2 10 000
3.3 10 000
3.4 10 000
4. 1 000; 10 000
5.
(i) twenty three thousand nine hundred and eighteen
(ii) forty seven thousand and seven
6.
6.1 A: 10 000
B: 12 500
C: 14 000
D: 16 500
E: 18 000
7.
7.1 10
7.2 100
7.3 1 000
7.4 60 000
7.5 100
7.6 10
7.7 36 567
7.8 16 824
7.9 3 612
7.10 10 000
1. If you know your tables very well it is easy to multiply and divide, especially with greater numbers. Work with a friend. See how quickly you can catch the correct fishes that go with the multiplication tables, by colouring them in.
1.1 8× table - green
1.2 9× table - blue
1.3 12× table - yellow
2. Now let us see whether you can improve your mental arithmetic skills! Work on your own and complete the following mental arithmetic test as quickly and accurately as possible! (Note: in Mathematics brackets mean “do that bit first”).
2.1 14 + 9 + 4 = _________________
2.2 Halve 137: _________________
2.3 30 × _________________ = 3000
2.4 (42 ÷ _________________) + 9 = 16
2.5 567 _________________ 23 = 590
2.6 9 × 6 = _________________
2.7 _________________ × 8 = 56
2.8 _________________ - 15 = 285
2.9 80 + 65 + 155 = _________________
2.10 1 003 - 19 = _________________
2.11 72 ÷ 9 = _________________
2.12 (5 × 6) + 13 = _________________
2.13 108 ÷ _________________ = 8
2.14 _________________ ÷ 12 = 6
2.15 Double 67: _________________
2.16 (5 × _________________) - 9 = 11
2.17 11 × 12 = _________________
2.18 _________________ ÷ 7 = 12
2.19 Round off to the nearest 100: 3 550 _________________
2.20 Round off to the nearest 1 000: 7 299_________________
Colour in:
My previous mental arithmetic mark was: | BETTER | WORSE | THE SAME |
3. In this activity it is important to look at the value and place value of every digit. Work with a friend and see whether you can answer the following questions:
3.1 Which number is 1 more than 9 999? _________________________________
3.2 Which number is 10 more than 9 990?________________________________
3.3 Which number is 100 more than 9 900?_______________________________
3.4 Which number is 1 000 more than 9 000?______________________________
3.5 The number 10 000 is 10 more than __________________________________
4 Let's see if you were right!
TEN THOUSANDS
DO YOU REMEMBER?
10 units = 10 × 1 = 10
10 tens = 10 × 10 = 100
10 hundreds = 10 × 100 = 1 000
4. Complete the following:
10 thousands = 10 × ......................... = .........................
In the notation column it looks like this:
× 10 × 10 × 10 × 10 | ||||
Ten thousands | Thousands | Hundreds | Tens | Units |
TT | T | H | T | U |
10 000 | 1 000 | 100 | 10 | 1 |
10 × 10 × 10 × 10 | 10 × 10 × 10 | 10 × 10 | 10 × 1 | 1 × 1 |
÷ 10 10 ÷ 10 ÷ 10 |
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