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Having fun with pocket calculators and negative numbers

Educator section


5. a) 108

b) 9

c) 13

d) 68

e) 14

f) 4

g) 48

h 72

i) 200

j) 18 000

k) 20

l) 9

m) R238

n) R6 080

o) 54

Leaner section


Activity: fun with the pocket calculator [lo 1.9.2

Fun with the pocket calculator

1. Did you know that pocket calculators are also able to “speak”? Take you pocket calculator and key in the following: 0,65 + 0,1234 =

Now turn your calculator upside-down. What do you read?


In this module we will be learning how to use the pocket calculator effectively in order to make calculating easy.


5 000 years ago the Babylonians designed a counting frame that they called an abacus. The Chinese still use a variation of this counting machine. Their abacus consists of beads that are moved along the rods of a counting frame.

In 1642 Blaise Pascal, who lived in France, designed a counting machine that was operated by turning knobs, but it was too expensive to produce.

Charles Babbage, a British mathematician, began working on a steam-driven analytical engine in 1830. For 37 years he worked on this engine that was able to do a variety of calculations, but died before he could finalise the design.


Work with a friend and find the following keys on your pocket calculator:

AC = Deletes everything, including the memory
C = Clears the screen
CE / CM = Clears the memory
Min / M / M+ _____________________________________
STO = Stores in the memory / adds
M- = Subtracts from the memory
RCL / x M _____________________________________
MR / RM = Recalls the memory
O m / O m = You did not clear the memory

Does your pocket calculator have another key that must be pressed to do the above? Write it here:






We have pocket calculators and scientific calculators.The latter are used for more complicated calculations.Compare your pocket calculator with those of your classmatesto see how they agree or differ.

5. Before we continue working with the pocket calculator, we are going to use some brainpower! Complete the following mental calculation test as quickly and accurately as possible:

a) 12 × 9 = __________

b) __________ × 7 = 63

c) 48 + __________ = 61

d) __________ - 18 = 50

e) 63 - __________ = 49

f) (12 × 8) + __________ = 100

g) 8 × 3 × 3 = __________

h) __________ ÷ 8 = 9

i) 80 × 40 = __________

j) 300 × 60 __________

k) 500 ÷ 25 = __________

l) one third of 27 = __________

m) R2,38 × 100 = __________

n) R6,08 × 1 000 = __________

o) __________ ÷ 6 = 9


Complete by colouring in the appropriate block:

This was GOOD AVERAGE POOR work!


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.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Mathematics grade 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11075/1.1
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