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If you are aware of the pattern in which 8; ..6; ..4; ..2; ..0; is repeated, and concentrate, you should be able to count in 8’s forever, without mistakes.

  • Now, work with a friend. Count in 8’s from 0 to 104 while your friend checks you on a calculator. Then swap over.

3.5 Now count backwards in 8’s from 104 to 0 while your friend checks you on a calculator.

Then swap over.

4. Multiples of 9

4.1 Do what Sue suggested. Write down the missing multiples of 9 in the flow diagram and look at the last digit of each one. Spot the pattern.

4.2 Counting in 9’s is the easiest of all! Now complete the table below.

1 2 3 4 5 6 7 8 9 10 11 12
× 9 9 18 27 90 99

4.3 Now count backwards in 9’s while a friend checks you on the calculator. Begin with 108.

Now you should feel comfortable when you count in 6’s; 7’s; 8’s and 9’s and you already know how to count in tens. Practise this with a friend, forwards and backwards.

TEST YOUR SKILLS

1. Complete the following by doing one column each day or all four columns in one day, or two columns per day, as your educator chooses:

(a) 7 × 4 =………… 6 × 8 =…………….. 8 × 9 =…………….. 2 × 8 =…………….
(b) 9 × 8 = 3 × 7 = 1 × 7 = 6 × 9 =
(c) 7 × 6 = 8 × 7 = 6 × 5 = 8 × 7 =
(d) 2 × 5 = 3 × 9 = 7 × 9 = 5 × 5 =
(e) 10 × 10 = 2 × 8 = 9 × 9 = 4 × 6 =
(f) 3 × 6 = 8 × 5 = 9 × 0 = 9 × 8 =
(g) 4 × 2 = 5 × 8 = 7 × 3 = 7 × 10 =
(h) 5 × 6 = 6 × 6 = 8 × 8 = 3 × 8 =
(j) 4 × 4 = 0 × 10 = 4 × 9 = 5 × 7 =
(k) 5 × 9 = 4 × 8 = 5 × 7 = 4 × 7 =
TOTAL: TOTAL: TOTAL: TOTAL:

2. Now write all those that you got wrong and write down a way of finding the correct answer for each of them.

Activity 2:

To do mental calculations involving multiplication of whole numbers [LO 1.9]

1. Now complete this flow diagram:

2. Ways of solving 7 x 8.

Example of solving 7 x 8.

  • 7 x 4 + 7 x 4 OR double (7 x 4)
  • 8 + 8 + 8 + 8 + 8 + 8 + 8
  • Counting in 8’s till you reach 7 x 8
  • 7 x 5 + 7 x 3 i.e. breaking up the 8 as we did previously
  • 2 x 8 + 5 x 8 i.e. breaking up the 7 to make it easier; I know 2 x 8 and 5 x 8
  • Double 3 x 8 + 8
  • 7 x 10 - 2 x 7Be sure that you know what you are doing!

3. Now take each one that bothers you, and find a way of reaching the answer without a calculator and write your solution in the table below.

My way of solving each problem:

e.g. 8 × 8 Double 4 × 8 =32 + 32 = 64
3 × 6 6 × 3 (I know my 3 times table) = 18

TEST YOUR SKILLS

  • Complete each of the following:

1.

2.

3.

4.

5.

6. Explain the link between 4 and 5.

7. Use what you have learnt in 4 and 5 to complete the following:

(a) 6 × 20 = (f) 40 × 20 =
(b) 7 × 70 = (g) 60 × 60 =
(c) 50 × 3 = (h) 50 × 80 =
(d) 9 × 70 = (j) 60 × 7 =
(e) 8 × 30 = (k) 90 × 50 =

Activity 3:

To estimate and calculate by selecting and using a range of techniques [LO 1.1, 1.8]

1. You have found ways of calculating answers of tables that you have not memorized. Now estimate the answer by rounding off. Estimations should be quick and easy, but they only give approximate answers. Then find ways of reaching the exact answer of the following sums and write down all your steps:

1.1 7 x 18

  • 24 x 6

Discuss your methods with other friends in your group.

1.3 36 x 54

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
Privacy Information Security Software Version 1.1a
Good
Read about ancient clocks like_ hour glass, water clock and sun dial for a quiz and hand on Activity in the class
Neha Reply

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Source:  OpenStax, Mathematics grade 4. OpenStax CNX. Sep 18, 2009 Download for free at http://cnx.org/content/col11101/1.1
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