# Numbers - where do they come from?  (Page 4/5)

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5.2 On a typical lightweight bed sheet, there might be about three threads per millimetre, both across and lengthwise. If a sheet for a double bed measured two metres square, that would mean 6,0 × 10 3 threads across plus another 6,0 × 10 3 threads lengthwise. That gives us 1,2 × 10 4 threads, each about two metres long. Calculate how many kilometres of thread it took to make the sheet. Tonight, measure your pillowslip and do the same calculation for it.

5.3 A typical raindrop might contain about 1 × 10 –5 litres of water. In parts of South Africa the annual rainfall is about 1 metre. On one hectare that means about 1 × 10 12 raindrops per year. On a largish city that could mean about 6 × 10 16 raindrops per year, or about 1 × 10 7 drops for every man, woman and child on Earth. How many litres each is that?

5.4 Calculate: (give answers in scientific notation)

5.4.1 $\frac{3,\text{501}×{\text{10}}^{-5}}{9,5×{\text{10}}^{-8}}+4,3×{\text{10}}^{-\text{11}}$

5.4.2 $\frac{3,5×{\text{10}}^{6}+1,4×{\text{10}}^{-\text{17}}}{3,5×{\text{10}}^{6}-1,4×{\text{10}}^{-\text{17}}}$

end of CLASS WORK

We use prefixes, mostly from Latin and Greek, to make names for units of measurement. For example, the standard unit of length is the metre . When we want to speak of ten metres, we can say one decametre; one hundred metres is a hectometre and, of course, one thousand metres is a kilometre. One tenth of a metre is a decimetre; one hundredth of a metre is a centimetre and one thousandth is a millimetre. There are other prefixes – see how many you can track down.

Your computer pals will be able to confirm, I hope, that in computers a “kilobyte” is really 1024 “bytes”. Now, why is it 1024 bytes and not 1000 bytes? The answer lies in the fact that computers work in the binary system and not in the decimal system like people. Try to find the answer yourself.

## Assessment

 Learning outcomes(LOs) LO 1 Numbers, Operations and RelationshipsThe 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 standards(ASs) We know this when the learner : 1.1 describes and illustrates the historical development of number systems in a variety of historical and cultural contexts (including local); 1.2 recognises, uses and represents rational num­bers (including very small numbers written in scientific notation), moving flexibly between equivalent forms in appropriate contexts; 1.3 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: 1.3.1 financial (including profit and loss, budgets, accounts, loans, simple and compound interest, hire purchase, exchange rates, commission, rentals and banking); 1.3.2 measurements in Natural Sciences and Technology contexts; 1.4 solves problems that involve ratio, rate and proportion (direct and indirect); 1.5 estimates and calculates by selecting and using operations appropriate to solving problems and judging the reasonableness of results (including measurement problems that involve rational approximations of irrational numbers); 1.6 uses a range of techniques and tools (including technology) to perform calculations efficiently and to the required degree of accuracy, including the following laws and meanings of exponents (the expectation being that learners should be able to use these laws and meanings in calculations only): 1.6.1 x n × x m = x n + m 1.6.2 x n  x m = x n – m 1.6.3 x 0 = 1 1.6.4 x –n = $\frac{1}{{x}^{n}}$ 1.7 recognises, describes and uses the properties of rational numbers.

#### Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
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.
Bharti
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
Daniel
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
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?
s. Reply
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
Devang Reply
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
Abhijith Reply
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?
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
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
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar 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 9. OpenStax CNX. Sep 14, 2009 Download for free at http://cnx.org/content/col11056/1.1
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 By Abishek Devaraj