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Wiskunde

Graad 4

Heelgetalle en hul verwantskappe

Module 3

Berekeninge met heelgetalle skriftelik en in hoofrekene

Aktiwiteit 1:

  • Om ‘n reeks tegnieke te gebruik om berekeninge met heelgetalle skriftelik en in hoofrekene uit te voer [LU 1.10]
  • Om te skat en te bereken met die selektering en gebruik van gepaste bewerkings vir die oplossing van probleme: afronding [LU1.8.1]
  • Om probleme op te los wat die vergelyking van twee of meer hoeveelhede van dieselfde soort behels (verhouding) [LU 1.7.1]
  • Om ‘n reeks strategieë te gebruik om oplossings te kontroleer en hulle redelikheid te beoordeel [LU 1.11]

SKATTING EN KONTROLERING VAN GERAAMDE ANTWOORDE

Ons het ”plekwaardes” bestudeer en nou gaan ons na die “afronding” van getalle kyk en sien hoe ons dit gebruik om:

  • geskatte antwoorde vinnig te bereken en ook
  • ons antwoorde vinnig te kontroleer.

1. SKATTING MET BEHULP VAN AFRONDING

Dink aan die volgende:

1.1 Jy ry op jou fiets na jou maat wat 10 km van jou af woon. Na 4 km bars een van jou buitebande. Waarheen gaan jy stap om dit reg te maak – terug na jou eie huis of gaan jy tot by jou maat se huis stap?

Natuurlik sal jy na jou eie huis terug stap – dis nader. 4 is nader aan 0 as aan 10.

1.2 Sê nou dat die band na 6 km bars. Sal jy weer besluit om terug huis toe te gaan of sal jy aanstap na jou maat se huis toe?

Ja, hierdie keer sal jy na jou maat se huis toe stap – dis nader.

6 is nader aan 10 as aan 0.

1.3 Hierdie keer bars die band nadat jy presies 5 km gery het. Sal jy besluit om terug huis toe te gaan of sal jy na jou maat se huis toe aanstap?

In Wiskunde rond jy altyd opwaarts af indien die laaste syfer 5 is.

  • Voltooi die volgende tabel:
Getal Afronding tot die naaste 10
54
1 345
278
978
245
1 133
684

1.5 Nou gaan ons “afronding” gebruik om 'n benaderde antwoord vinnig vir die volgende somme te bereken, en daarna sal ons die presiese antwoord bereken en die verskil tussen die twee antwoorde bereken. Vul in wat in die kolomme ontbreek:

Som Getalle afgerond tot die naaste 10 Geskatte antwoord Presiese antwoord Verskil tussen die 2 antwoorde
24 + 36 20 + 40
52 + 48 50 + 50
33 + 52
79 + 23
17 + 47
125 + 46
411 + 732

1.6 Kyk na die somme wat jy so pas voltooi het. In watter van hierdie somme was die geskatte en die werklike antwoorde taamlik ver van mekaar, en hoekom was dit so?

AFRONDING TOT DIE NAASTE 100:

1.7 Voltooi die volgende tabel.

Getal Afgerond tot die naaste 100
256
304
549
1 207
1 399

AFRONDING TOT DIE NAASTE 1 000:

1

1.8 Voltooi die tabel hieronder. Indien jy onseker voel, kan jy die diagram in 1.9 raadpleeg.

Getal Getal afgerond tot die naaste 1 000
500
1 702
4 089
723
1 055
276

1.9 Gebruik afronding om antwoorde vir die volgende somme te skat. Daarna moet jy die korrekte antwoord bereken.

Die som met die presiese antwoord. Die som met die getalle tot die naaste 10 afgerond en die geskatte antwoord.
873 + 46
934 - 87

2. WOORDSOMME

  • Kom ons kyk hoe goed ons woordsomme sonder ‘n sakrekenaar kan oplos. Kontroleer dat jou antwoorde redelik is deur die getalle af te rond. Onthou dat jou finale antwoorde presies moet wees. Die getalle is nie baie groot nie en die somme is redelik eenvoudig, maar jy moet versigtig lees. Skryf wat nodig is om te skryf en onthou om woorde by jou antwoorde te skryf. Wanneer jy die werk voltooi het, kan jy jou bevindings met dié van ‘n maat vergelyk. Geniet hierdie taak!

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, Wiskunde graad 4. OpenStax CNX. Sep 18, 2009 Download for free at http://cnx.org/content/col11100/1.1
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