# 3.2 Decimal fractions and rounding off

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## Memorandum

• a) 41c
1. 42 $\frac{1}{2}$
2. 44c
• Rounding off

11.3.1 a) Look at the 2 nd digit after comma (100ths)

If 5, 6, 7, 8, 9: 10ths – digit 1 more

If 4, 3, 2, 1, 0: 10ths – digits remains the same

Replace everything after 10ths with noughts

1. Look at 3 rd digit after comma

If 5, 6, 7, 8, 9: 100ths – digit 1 more

If 4, 3, 2, 1, 0: 100ths – digit remains the same

Replace everything after 100ths with noughts

1. Look at 4 th digit after comma

If 5. 6, 7, 8, 9: Thousandths 1 more

If 4, 3, 2, 1, 0: Thousandths temain the same

Replace everything after 1 000ths with noughts

11.4 a) 4,5

9,9

5,3

7,6

52,6

88

11.4 b)

 6,41 8,60 7,26 9,49 5,03 6,29

11.4 c) (i) (ii)

(iii) (iv)

• (vi)

12.2 a) 11

1. R406
2. 6
3. 5
4. R327
5. 8
6. 9
7. 14
8. 448
9. 1 390

## Activity: decimal fractions and rounding off [lo 1.4.2, lo 1.7.1]

11.1 DECIMAL FRACTIONS AND ROUNDING OFF

Work together with a friend. Look at the sketches. What does one potato cost in each case?

11.2 Round off the following to the nearest whole number. Write down the corresponding letter and see what word is hiding away.

 B D E F G I K 39 149 7 236 38 6 17
 L M N O R S T U 237 15 35 16 8 150 3 4

a) 8,047

b) 15,51

c) 3,7

d) 35,236

e) 149,089

f) 6,4

g) 35,09

h) 38,456

i) 15,912

j) 236,199

k) 235,89

11.3.1 Work in groups of three. Formulate rules/methods for the following:

a) Rounding off to one decimal place (tenths):

b) Rounding off to two decimal places (hundredths):

c) Rounding off to three decimal places (thousandths):

11.3.2 Compare your answers with those of the rest of the class.

11.4

a) Complete the following flow diagram:

b) See if you can complete the table correctly:

 Number 4,368 6,411 8,599 7,255 9,493 5,034 6,286 Rounded off to 2 decimal places 4,37 ............. ............. ............. ............. ............. .............

c) Round off the following to 3 decimal places. Draw a circle around the correct answer:

12.1 Do you still remember?

1 000 ml = 1 litre

1 000 g = 1 kg

1 000 kg = 1 tonne

1 000 litres = 1 k

1 000 m = 1 km

100 c = R1,00

12.2 Fill in the missing answers:

e.g. 3 521 mm to the nearest m = 4 m

a) 11 296 mm to the nearest m = ......................... m

b) R406,38 to the nearest rand = R.........................

c) 6 455 litre to the nearest kl = ......................... kl

d) 4 823 kg to the nearest tonne = ......................... t

e) 32 687 c to the nearest rand = R.........................

f) 8 388 g to the nearest kg = ......................... kg

g) 8 630 m to the nearest litre = ......................... litres

h) 14 277 m to the nearest km = ......................... km

i) R4,4839 to the nearest cent = ......................... c

j) R13,9021 to the nearest cent = ......................... c

## 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 1.4 We know this when the learner recognises and uses equivalent forms of the rational numbers listed above, including:

1.4.2 decimals;

Assessment Standard 1.7: We know this when the learner estimates and calculates by selecting and using operations appropriate to solving problems that involve:

1.7.1 rounding off numbers to at least one decimal place.

#### Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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