1.14 Fun with the pocket calculator

Mathematics

Having fun with pocket calculators and negative numbers

Educator section

Memorandum

6. a) get dressed and eat

clean different rooms in the house

order in which you do your homework

learners gives own answers

1. first draw money and then do your shopping

fisrt learn your work and then write a test

cover books; plastic last

throw petrol in first and then ride

learners give own answers

8. a) 66

1. 0
2. 9
3. 223
4. 153

Leaner section

Content

Activity: fun with the pocket calculator [lo 1.9.2

6 SEQUENCE OF CALCULATIONS

If you do not know the sequence in which you have to do calculations, the pocket calculator will not be of any help to you - it will actually help you out of the frying pan into the fire!

Discuss the following:

a) Does it matter if you put the milk into the teacup before pouring the tea, or the tea before the milk?

b) Do you brush your teeth before breakfast or do you eat first and then brush your teeth?

c) Give examples of where the sequence in which you do things does not matter.

d) Give examples of where the sequence matters/is important.

7 MORE REVISION

We work from left to right when we do repeated addition and subtraction.

e.g. 20 – 5 + 12 – 5 – 2 = 20

We work from left to right for repeated multiplication and division.

e.g. 6 × 3 ÷ 2 = 9

In the case of mixed calculations, the sequence is:

8. Use your pocket calculator to find the answers to the following:

a) 100 – 4 × 5 – half of 28

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b) 26 × 54 – 54 × 26

______________________________________________________________c) 200 ÷ 20 + 285 ÷ 95 – 8 + 4

______________________________________________________________d) 382 – (129 + 31) + one third of 3

______________________________________________________________

e) (65 – 15) × 3 + 21 ÷ 7

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Assessment

Learning Outcome 1: The learner will be 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 Standard 1.9: We know this when the learner uses a range of techniques to perform calculations including:

1.9.2: using a calculator.