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
- 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
- 0
- 9
- 223
- 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:
| ( ) brackets |
| of |
| ÷ |
| × |
| + |
| - |
8. Use your pocket calculator to find the answers to the following:
a) 100 – 4 × 5 – half of 28
______________________________________________________________
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
______________________________________________________________
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.