# OpenStax-CNX

You are here: Home » Content » Wiskunde Graad 5 » Om te skat en te bereken deur gepaste bewerkings toe te pas

### Lenses

What is a lens?

#### Definition of a lens

##### Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

##### What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

##### Who can create a lens?

Any individual member, a community, or a respected organization.

##### What are tags?

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

#### In these lenses

• GETIntPhaseMaths

This module and collection are included inLens: Siyavula: Mathematics (Gr. 4-6)
By: Siyavula

Module Review Status: In Review
Collection Review Status: In Review

Click the "GETIntPhaseMaths" link to see all content selected in this lens.

Click the tag icon to display tags associated with this content.

### Recently Viewed

This feature requires Javascript to be enabled.

### Tags

(What is a tag?)

These tags come from the endorsement, affiliation, and other lenses that include this content.

Inside Collection (Course):

Course by: Siyavula Uploaders. E-mail the author

# Om te skat en te bereken deur gepaste bewerkings toe te pas

Module by: Siyavula Uploaders. E-mail the author

## Memorandum

1. Kyk na die ene syfer.

Indien dit 5 of meer is, word die tiene-syfer een meer.

Indien dit 4 of minder is, bly die tiene-syfer dieselfde.

2. Kyk na die tiene-syfer.

Indien dit 5 of meer is, word die honderde-syfer een meer.

Indien dit 4 of minder is, bly die honderde-syfer dieselfde.

3. Kyk na die honderde-syfer.

Indien dit 5 of meer is, word die duisende–syfer een meer.

Indien dit 4 of minder is, bly die duisende-syfer dieselfde.

2.

2.1 20 + 10 + 20 = 50

2.2 30 + 10 + 50 = 90

2.3 10 + 20 + 20 = 50

2.4 100 + 200 + 300 = 600

2.5 200 + 100 + 100 = 400

3. “Geskatte Antwoord” en “Verskil” sal verskil a.g.v. metode gebruik. Dus net die sakrekenaar antwoord:

4.

a) 279

b) 1 660

c) 6 581

d) 2 843

5. Antwoorde kan verskil – daar is duisende kombinasies!

6. 35 + 15; 47 + 3; 23 + 27

50 + 150; 25 + 175; 10 + 190; 180 + 20; 170 + 30

250 + 750; 400 + 600; 900 + 100; 200 + 800; 990 + 10

6. 250 + 750; 125 + 825; 950 + 50; 450 + 550; 225 + 775; 415 + 585

7. 5 000 + 400 + 80 + + 9 + 300 + 60 + 2 + 1 000 + 500 + 70

= (5 000 + 1 000) + (400 + 300 + 500) + (80 + 60 + 70 +) + (9 + 2)

= 6 000 + 1 200 + 210 + 11

= 7 421

## Inhoud

### AKTIWITEIT: Om te skat en te bereken deur gepaste bewerkings toe te pas [LU 1.8]

• Kom ons oefen nou jou bekwaamheid om met vertroue antwoorde te skat deur getalle af te rond!

1. Dit is belangrik dat ons net weer sal kyk wat “afronding” is en hoe ‘n mens dit doen. Verduidelik gou aan ’n maat hoe ons afrond tot die naaste 10, 100 en 1 000.

2. Werk nou in groepe van drie en kyk wie eerste die antwoorde sonder ’n sakrekenaar kan bereken deur af te rond tot die naaste 10 of 100. (Jy mag niks neerskryf nie!)

2.1 16 + 11 + 19

2.2 34 + 9 + 52

2.3 2 + 15 + 23

2.4 141 + 208 + 339

2.5 182 + 149 + 106

3. Kyk nou goed na die volgende voorbeeld:

32 + 87 + 96 + 42 word30 + 90 + 100 + 40 (afgerond tot die naaste 10))

Die antwoord is dus naastenby 260.

• Wanneer ons groter getalle wil optel, kan ons tot die naaste 100 afrond:

138 + 759 + 304 word100 + 800 + 300Die antwoord sal dus naastenby 1 200 wees.

HET JY GEWEET?

• Ons kan ook getalle na ’n onderste en boonste grens afrond!

Bv. 62 + 75 + 94 + 45

Onderste grens: 60 + 70 + 90 + 40 = 260

Boonste grens: 70 + 80 + 100 + 50 = 300

Die korrekte antwoord lê dus tussen 260 en 300.

4. Voltooi nou die tabel deur die getalle af te rond volgens die metode wat jy verkies. Skat eers die antwoord. Bereken dan die korrekte antwoord met ’n sakrekenaar. Skryf dan die verskil tussen die twee antwoorde neer.

 Berekening Geskatte antwoord Sakrekenaar Verskil Bv. 308 + 475 300 + 480 = 780 783 3 a) 67 + 98 + 114 b) 896 + 723 + 41 c) 1 892 + 4 689 d) 2 458 + 294 + 91

TYD VIR SELFASSESSERING

Kleur die korrekte blokkie in:

 Ek het die vaardigheid om op te tel d.m.v. op- en afronding tot die naaste 10, 100 of 1 000 bemeester. **nog nie bemeester nie.

** Vra jou opvoeder om nog voorbeelde vir jou te gee wat jy tuis kan oefen.

5. Daar is nog ander tegnieke of bewerkings (behalwe afronding) wat jy kan gebruik om antwoorde vinnig te bereken. Kyk goed na die voorbeelde en probeer dan om nog getalkombinasies by te voeg.

6. Kyk nou na die getalle in die +-teken. Deur soveel moontlik optelstringe wat ‘n som van 1 000 gee, te vind , kan jy die som van al die getalle in ‘n japtrap bereken. Hoeveel sien jy? Kleur hulle dieselfde in.

Tabel 3
250
585
125
750 825 50
 950 450
550 775 415
225
316
775
415

ONTHOU JY NOG?

Ons kan groepering gebruik om op te tel. Kyk goed na die voorbeeld.

• = 370 + 245 + 684

= 300 + 70 + 200 + 40 + 5 + 600 + 80 + 4

= (300 + 200 + 600) + (70 + 40 + 80) + (5 + 4)

= 1 100 + 190 + 9

• = 1 299

7. Gebruik nou hierdie metode en bereken:

5 489 + 362 + 1 570

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

## Assessering

Leeruitkomste 1:Die leerder is in staat om getalle en die verwantskappe daarvan te herken, te beskryf en voor te stel, en om tydens probleemoplossing bevoeg en met selfvertroue te tel, te skat, te bereken en te kontroleer.

Assesseringstandaard 1.8: Dit is duidelik wanneer die leerder skat en bereken deur geskikte bewerkings vir die oplossing van probleme te gebruik:

1.8.1 afronding tot die naaste 5, 10, 100 of 1 000;

1.8.2 optel en aftrek van heelgetalle met minstens 5 syfers.

## Content actions

PDF | EPUB (?)

### What is an EPUB file?

EPUB is an electronic book format that can be read on a variety of mobile devices.

#### Collection to:

My Favorites (?)

'My Favorites' is a special kind of lens which you can use to bookmark modules and collections. 'My Favorites' can only be seen by you, and collections saved in 'My Favorites' can remember the last module you were on. You need an account to use 'My Favorites'.

| A lens I own (?)

#### Definition of a lens

##### Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

##### What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

##### Who can create a lens?

Any individual member, a community, or a respected organization.

##### What are tags?

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

| External bookmarks

#### Module to:

My Favorites (?)

'My Favorites' is a special kind of lens which you can use to bookmark modules and collections. 'My Favorites' can only be seen by you, and collections saved in 'My Favorites' can remember the last module you were on. You need an account to use 'My Favorites'.

| A lens I own (?)

#### Definition of a lens

##### Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

##### What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

##### Who can create a lens?

Any individual member, a community, or a respected organization.

##### What are tags?

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

| External bookmarks