= ......................... ÷ ..................
= ..................
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?
Activity 7:
To be able to do mental arithmetic [lo 1.9.2]
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.
Activity 8:
To estimate and calculate by using selected computations [lo 1.8.5]
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.
Activity 9:
To be able to solve problems in context [lo 1.6.1]
- The following activity is a group project that you can add to your portfolio. Your educator will provide you with the necessary paper and will explain exactly what you are expected to do.
- Divide into groups of four or five and then read the assignment closely.
- Your group must visit at least three florists or flower vendors in your area. Your job is to determine which florist or vendor is the cheapest.