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2. Now compare your answer with that of a group that had to solve the same problem.
3. Explain your solution to the rest of the class.
4. Have a class discussion on the differences / similarities in your methods.
1. We have just solved a few problems and discussed the different ways to determine the answers. Work with a friend, read the following problem and take a good look at the given solutions. Make sure that you understand how the answer has been calculated.
A restaurant uses 9,786 ℓ milk during breakfast and 5,463 ℓ for supper. How much less milk is used for supper?
1.1 I must calculate 9,786 – 5,463
I first subtract the whole numbers : 9 – 5 = 4
Then I subtract the thousandths : $\frac{6}{\text{1000}}$ − $\frac{3}{\text{1000}}$ = $\frac{3}{\text{1000}}$
Now I subtract the hundredths : $\frac{8}{\text{100}}$ − $\frac{6}{\text{100}}$ = $\frac{2}{\text{100}}$
Lastly I subtract the tenths : $\frac{6}{\text{10}}$ − $\frac{3}{\text{10}}$ = $\frac{3}{\text{10}}$
Now I add the answers: 4 + $\frac{3}{\text{10}}$ + $\frac{2}{\text{100}}$ + $\frac{3}{\text{1000}}$ = 4.323
The difference is thus 4,323 ℓ.
1.2 I do it in precisely the same way as normal subtraction but I write the commas precisely underneath each other :
9,786
− 5,463
4,323
The restaurant uses 4,323 ℓ less milk at supper time.
2. Whose method do you choose?
Why?
1. Now use any method and calculate the following without a calculator:
1.1: 6,42  2 98
1.2: 7,23  4,57
1.3: 8,123  3,545
1.4: 9,236  3,457
2. Check your answers with a calculator.
Brainteaser!
Calculate 5 – 1,426
Here is a challenge!
This assignment can be placed in your portfolio. Make sure that you read the criteria for assessment very carefully before you start. Ask your teacher for the necessary paper.
1. Look for examples of decimal fractions in your local newspaper or your favourite magazine. Cut them out neatly and paste them in below.
2. Write the decimal fractions as ordinary fractions next to or below the ones you have pasted in.
3. Now calculate the difference between the greatest and the smallest decimal fraction.
4. Calculate the sum of the two greatest decimal fractions.
5. Make a list of objects for which you would not use decimal fractions. Make a neat sketch of these objects.
LO 1 
Numbers, Operations and RelationshipsThe learner is able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems. 
Assessment standards(ASs) 
We know this when the learner: 
1.3 recognises and represents the following numbers in order to describe and compare them: 
1.3.3 decimal fractions of the form 0,5; 1,5; 2,5, and so on, in the context of measurement; 
1.5 recognises and uses equivalent forms of the numbers listed above, including: 
1.5.2 decimal fractions of the form 0,5, 1,5 and 2,5, and so on, in the context of measurement; 
1.6 solves problems in context including contexts that may be used to build awareness of other Learning Areas, as well as human rights, social, economic and environmental issues such as:

1.8 estimates and calculates by selecting and using operations appropriate to solving problems that involve:

1.9 performs mental calculations involving:1.9.1 addition and subtraction;1.9.2 multiplication of whole numbers to at least 10 x 10; 
1.10 uses a range of techniques to perform written and mental calculations with whole numbers including:

1.11 uses a range of strategies to check solutions and judge the reasonableness of solutions; 
ACTIVITY 2
3. Actually the same
ACTIVITY 3
1. 1.1: 157,727
1.2: 44,519
1.3: 142,498
1.4: 290,126
2. 4,5 m
BRAINTEASER!
0,8; 2,4; 1,9;
0,7; 0,3; 2,5; 2,1;
0,2; 0,9; 2,7;
ACTIVITY 6
1. 1.1: 3,44
1.2: 2,66
1.3: 4,578
1.4: 5,779
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