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100 × 2 700 = .........................
Does your rule “work” for 0,2 × 100?
1. In our previous module we looked at the associative and commutative characteristics of addition – do you remember this? There are similar characteristics of multiplication. Do you want to know how it works? Fill in the missing factors to balance the equasions:
8 x 6 = 6 x ____
23 x ____ = 13 x 23
124 x 85 = ____ x 124
2. Is the following true or false?
2.1 6 × 3 × 4 = 3 × 4 × 6 = 4 × 6 × 3 ..................................................
2.2 (2 × 4) × 5 = (5 × 4) × 2 = 4 × (2 × 5) ..................................................
3. What do you realise from the above examples?
1. To be able to estimate answers is an important skill. If you are good at estimating, it will be easier for you to realise that you may have made a mistake in your calculations. Round off the following numbers first and in this way you will be able to estimate what the product of each of the following will be:
SUM | ESTIMATE | CALCULATOR | DIFFERENCE |
E.g. 19 × 21 | 400 | 399 | 1 |
a) 38 × 27 | ......................... | ......................... | ......................... |
b) 99 × 146 | ......................... | ......................... | ......................... |
c) 45 × 69 | ......................... | ......................... | ......................... |
d) 998 × 78 | ......................... | ......................... | ......................... |
e) 409 × 18 | ......................... | ......................... | ......................... |
BRAIN-TEASERS!
a) Which two numbers, smaller than 10, have 3 factors each?
......................... and .........................
b) Colour in the correct block:
The product of 2 uneven numbers is always an | EVEN | UNEVEN | number. |
c) Which two numbers have a product of 48 and a sum of 16?
......................... and .........................
Let’s do some brainstorming now. Your teacher will give you the necessary paper.
1. Split up into groups of three and, as quickly as possible, make a list of all the means of transportation that exist in our country.
2. Which of the above-mentioned would you choose if you had to travel? Why?
3. Where is your favourite seat in:
4. Now see whether you are able to solve the following problems:
Messrs Slobo, Mugathle and Sisula have each bought a brand new taxi with which to transport passengers. For their first trip their plans are the following:
Owner | Amount per person | Number of passengers | km travelled |
Slobo | R15,80 | 13 | 76 |
Mugathle | R14,60 | 14 | 84 |
Sisula | R16,25 | 12 | 59 |
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