# Multiplication

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100 × 2 700 = .........................

• Write a rule for multiplying any number by 100:

Does your rule “work” for 0,2 × 100?

## To recognise and use the characteristics of multiplication with whole numbers [lo 1.12.3]

1. In our previous module we looked at the associative and commutative characteristics of addition – do you remember this? There are similar characteristics of multiplication. Do you want to know how it works? Fill in the missing factors to balance the equasions:

8 x 6 = 6 x ____

23 x ____ = 13 x 23

124 x 85 = ____ x 124

2. Is the following true or false?

2.1 6 × 3 × 4 = 3 × 4 × 6 = 4 × 6 × 3 ..................................................

2.2 (2 × 4) × 5 = (5 × 4) × 2 = 4 × (2 × 5) ..................................................

3. What do you realise from the above examples?

## To estimate and calculate by means of rounding off [lo 1.8.1]

1. To be able to estimate answers is an important skill. If you are good at estimating, it will be easier for you to realise that you may have made a mistake in your calculations. Round off the following numbers first and in this way you will be able to estimate what the product of each of the following will be:

 SUM ESTIMATE CALCULATOR DIFFERENCE E.g. 19 × 21 400 399 1 a) 38 × 27 ......................... ......................... ......................... b) 99 × 146 ......................... ......................... ......................... c) 45 × 69 ......................... ......................... ......................... d) 998 × 78 ......................... ......................... ......................... e) 409 × 18 ......................... ......................... .........................

BRAIN-TEASERS!

a) Which two numbers, smaller than 10, have 3 factors each?

......................... and .........................

b) Colour in the correct block:

 The product of 2 uneven numbers is always an EVEN UNEVEN number.

c) Which two numbers have a product of 48 and a sum of 16?

......................... and .........................

## Activity 9 :

• To be able to solve problems in context [LO 1.6.1]
• To be able to use a series of techniques to do calculations [LO 1.10]

Let’s do some brainstorming now. Your teacher will give you the necessary paper.

1. Split up into groups of three and, as quickly as possible, make a list of all the means of transportation that exist in our country.

2. Which of the above-mentioned would you choose if you had to travel? Why?

3. Where is your favourite seat in:

1. a car
2. a school bus
3. a boat
4. an aeroplane

4. Now see whether you are able to solve the following problems:

Messrs Slobo, Mugathle and Sisula have each bought a brand new taxi with which to transport passengers. For their first trip their plans are the following:

 Owner Amount per person Number of passengers km travelled Slobo R15,80 13 76 Mugathle R14,60 14 84 Sisula R16,25 12 59
• Who made the most money with the first trip?
• If the petrol cost R1,05 for every kilometre that was travelled, how much did Mr Mugathle’s petrol account come to?
• If all the passengers in Mr Slobo’s taxi were athletes and they had to run back, how far did they run altogether?
• Explain to the rest of the class how your group calculated the answers.
• Compare your methods. How do your methods differ?
• Check the answers, using a pocket calculator.

#### Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
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?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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
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 5. OpenStax CNX. Sep 23, 2009 Download for free at http://cnx.org/content/col10994/1.3
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