<< Chapter < Page Chapter >> Page >

Mathematics

Grade 4

Numbers, feactions, decimals and number patterns

Module 9

Recognise and represent fractions

Activity 1:

To recognise and represent decimal fractions [LO 1.3]

RECOGNIZING DECIMALS

1. What are decimals?

1.2 Think back to Place Value: Thousands; Hundreds; Tens and Units.

Complete the following:

1 000  10 = 100
100  10 =
10  10 =
110 = ?

1.3 Now check your answers on the calculator.

The calculator says that 1 10 = 0,1. What does 0,1 then mean? Discuss with a friend.

1.4 Draw lines on the bar below to show tenths. One has been divided by 10. We say that 0,1 is one tenth. It is the only way in which calculators can write one tenth, because of the way that they have been programmed. Now label each section on the bar below 0,1.

What is the meaning of 0,1? We have found that 1  10 = 0,1.

Think back to Fractions: we said: 1  2 = 1 2 size 12{ { {1} over {2} } } {}

So 1  10 = 1 10 size 12{ { {1} over {"10"} } } {}

1  10 = 1 10 size 12{ { {1} over {"10"} } } {} = 0,1

0,1 is just another way of writing 1 10 size 12{ { {1} over {"10"} } } {}

Study the diagram:

Thousands1 000 Hundreds100 Tens10 Units1 Tenths
Thousands1 000 Hundreds100 Tens10 Units1 Tenths 1 10 size 12{ { {1} over {"10"} } } {}
7 1 9 3 6
5 0 6 9 1

How do we show the end of the whole number when there are no headings?

We use a DECIMAL COMMA.

What are the numbers that have been written in the columns?

  • 7 193, 6 = 7 × 1 000 + 1 × 100 + 9 × 10 + 3 × 1 + six tenths
  • 5 069,1 = 5 × 1 000 + 0 + 6 × 10 + 9 × 1 + 1 10 size 12{ { {1} over {"10"} } } {}

Our calculators cannot write common fractions as we can; they are only machines that have been programmed to use place value, so they can only write decimal fractions.

Remember: We use a DECIMAL COMMA

to show the END OF THE WHOLE NUMBER

and the BEGINNING OF THE DECIMAL FRACTION

2. Now write the following decimal numbers in their expanded form under the correct heading in the columns below:

2.1 (a) 1 456,3 (b) 4 601,9 (c) 8,5 (d) 31, 7 (e) 456,2

X 1 000 × 100 × 10 × 1 × 0,1(tenths)
(a)
(b)
(c)
(d)
(e)

The FIRST digit after the decimal comma is always TENTHS.

2.2 Now write them again in their expanded form:

(a) 1 456,3 = 1 × 1 000 + 4 × 100 + 5 × 10 + 6 × 1 + 3 × 0,1

Activity 2:

To compare fractions [LO 1.5]

1. Carefully consider the value of each digit and use the correct sign from:<;  ; = to>compare the following:

1.1 1,5 _____1,7 1.4 45,9 ____62,3

1.2 6,3 ____ 6,1 1.5 13,2 ____8,6

1.3 24,7____ 42,3 1.6 57,5 ____58,2

2. Encircle the largest number:

43,7; 41,9; 43,1; 49,1; 41,5

3. Write down the number that is:

Answer Answer
3.1 one more than 9,9 3.1 3.5 0,1 less than 7,1 3.5
3.2 0,1 more than 5,3 3.2 3.6 0,1 more than 99,0 3.6
3.3 0,1 less than 6 3.3 3.7 0,1 more than 5,8 3.7
3.4 0,1 less than 8,3 3.4 3.8 0,1 less than 10 3.8

Activity 3:

To convert from fractions to decimal fractions and vice versa [LO 1.5]

Group discussion.

1. Read the following conversation between John and Sarah.

  • Was Sarah’s answer correct? It did not seem to help John completely. Where did the ,5 come from? Discuss. Try to explain why half = 0,5 on a calculator.
  • Which of you were wide awake? All of you? Did you all know? Wonderful! Yes, it’s because the calculator counts in tenths and five-tenths = one-half. The poor calculator has to use equivalent fractions to make tenths from things like halves and quarters and any fractions that are not tenths (hundredths and thousandths, but they come later).

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
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

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Mathematics grade 4. OpenStax CNX. Sep 18, 2009 Download for free at http://cnx.org/content/col11101/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Mathematics grade 4' conversation and receive update notifications?

Ask