# Multiplication

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## To be able to use a series of techniques to do calculations [lo 1.10.5]

By now you know how to multiply by smaller numbers. Now we are going to see whether you are also able to do calculations with bigger numbers. Split up into groups of 3 and ask your teacher to give you the paper you need. Then read the instructions very carefully.

Michaela and her friends visited the zoo and heard the following interesting facts: a hippopotamus eats 45 kg of fodder per day, while a large bull elephant needs 225 kg of fodder per day!

1. How many kilograms of fodder will 329 hippopotamuses eat per day?

2. How many kilograms of fodder must the zoo buy per day to feed 76 bull elephants?

3. If the entrance fee was R15 per person and 475 people visited the zoo that day, how much money was taken at the entrance gate?

4. Explain to the rest of the class how your group calculated the answers.

5. Compare your methods. How do the various methods differ from each other?

6. Use a pocket calculator to check the answers.

## To use strategies to check solutions [lo 1.11]

1. In the previous activity you probably noticed that there is more than one method to do multiplication. Split up into groups of 3 again. Look carefully at the solutions to the following problem and explain the methods to one another.

Mrs Cele sells clothes. There are 46 different pairs of jeans and 238 different shirts. How many combinations can she make up?

1.1 I calculate 46 × 238 in this way

238 × 46 = (200 + 30 + 8) × (40 + 6)

200 × 40 = 8 000

30 × 40 = 1 200

8 × 40 = 320

200 × 6 = 1 200

30 × 6 = 180

8 × 6 = 48

10 948

1.2 I write it in this way:

238

× 46

48 (8 × 6)

180 (30 × 6)

1 200 (200 × 6)

320 (40 × 8)

1 200 (40 × 30)

8 000 (40 × 200)

10 948

1.3 My method looks like this:

2 2 4 3 8

× 4 6

1 4 2 8

9 5 2 0

1 0 9 4 8

2. Now use any method that you understand and with which you feel comfortable, and calculate the product of:

2.1 576 × 47

2.1 576 × 47

CHALLENGE!

Can you calculate the product of the following by using the method shown in 1.3?

1. 347 × 251

2. 526 × 438

ANOTHER BRAIN-TEASER

Study the following sum carefully: 24 × 13 = 377

One of the digits is incorrect. Can you find out which one it is? ..............

What must it be? .........................

## To solve problems in context [lo 1.6.1]

Let’s go out to dinner.

This assignment is for your portfolio. Your teacher will go through it with you and explain exactly what you are expected to do. Make sure that you understand perfectly before you start. Remember to work neatly.

Form groups of three. Your group decides to eat something from each section of the menu. To make it easier for the waiter, each person in your group chooses the same soup, starter, main course and dessert.

Decide what you are going to order and then calculate your account. Use the block below. You may use a calculator. First estimate what the meal will cost the group. ..............................

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
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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