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= ......................... ÷ ..................
= ..................
DID YOU KNOW?
We can also break up the divisor into factors :
E.g. 108 ÷ 12 = 108 ÷ 4 ÷ 3 = 27 ÷ 3 = 9
OR
108 ÷ 12 = 108 ÷ 2 ÷ 6 = 54 ÷ 6 = 9
3. Calculate the following by breaking up the divisor into factors :
3.1 105 ÷ 21 = ...................................... 3.2 216 ÷ 24 = ......................................
= ...................................... = ......................................
= ...................................... = ......................................
3.3 432 ÷ 24 = ...................................... 3.4 126 ÷ 14 = ......................................
= ...................................... = ......................................
= ...................................... = ......................................
4. Work together with a friend. Look carefully at the following and then explain it to two other friends.
4.1 184 ÷ 4 = (180 + 4) ÷ 4
= (180 ÷ 4) + (4 ÷ 4)
= 45 + 1
= 46
4.2 2 515 ÷ 5 = (2 000 + 500 + 15) ÷ 5
= (2 000 ÷ 5) + (500 ÷ 5) + (15 ÷ 5)
= 400 + 100 + 3
= 503
4.3 3 672 ÷ 12 = (3 600 ÷ 12) + (72 ÷ 12)
= 300 + 6
= 306
5. Complete the following:
5.1 3 045 ÷ 15 = (3 000 + ....................) ÷ 15
= (.................... ÷ 15) + (.................... ÷ 15)
= 200 + ....................
= ....................
5.2 2 575 ÷ 25 = (2 000 + .................... + ....................) ÷ 25
= (2 000 ÷ 25) + (.................... ÷ .............) + (............. ÷ ............)
= .................... + .................... + ....................
= ....................
5.3 Can you write down your own explanation?
1. Let us test your mental skills again. Find the correct answer and encircle it with your pencil. Find out who or what is hidden away.
1.1 96 ÷ 12
1.2 108 ÷ 9
1.3 72 ÷ 9
1.4 42 ÷ 6
1.5 54 ÷ 6
1.6 32 ÷ 8
1.7 27 ÷ 9
1.8 66 ÷ 11
1.9 81 ÷ 9
1.10 35 ÷ 7
1.11 21 ÷ 3
1.12 ____ ÷ 6 = 9
1.13 ____ ÷ 8 = 6
1.14 ____ ÷ 6 = 12
1.15 ___ ÷ 11 = 12
1.16 ____ ÷ 9 = 5
1.17 ____ ÷ 7 = 8
1.18 Halve: 96
1.19 Halve: 134
1.20 Halve: 576
Colour the pictures in neatly so that your answers are clearly visible.
1. We have already discussed the value of estimation . Let us see again how well you can estimate. Encircle the best answer.
I ESTIMATE | ||||
a) | How many 16’s are there in 35? | 2 | 12 | 20 |
b) | How many 15’s are there in 93? | 6 | 16 | 60 |
c) | How many 13’s are there in 271? | 2 | 20 | 200 |
d) | How many 25’s are there in 4 130? | 27 | 175 | 750 |
e) | How many 21’s are there in 8 565? | 4 | 40 | 400 |
2. Now use your calculator to see whether you were spot on.
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