Skip to content Skip to navigation Skip to collection information

OpenStax-CNX

You are here: Home » Content » Mathematics Grade 5 » To improve your mental arithmetic skills

Navigation

Table of Contents

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? tag icon

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

This content is ...

In these lenses

  • GETIntPhaseMaths display tagshide tags

    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 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.
 

To improve your mental arithmetic skills

Module by: Siyavula Uploaders. E-mail the author

MATHEMATICS

Number Concept, Addition and Subtraction

EDUCATOR SECTION

Memorandum

1. 11; 25; 6; 12; 11; 15; 27; 34

24; 8; 14; 9; 17; 13; 11; 12

2.

2.1 519; 527; 535; 543

2.2 825; 810; 795; 780

2.3 3 770; 3 779; 3 797; 3 806

2.4 99 800; 9 760; 9 640; 9 600

3.

3.1 3 003; 333; 330; 303; 33

3.2 6 666; 6 606; 6 600; 6 060; 6 006

Leaner Section

Content

ACTIVITY: To improve your mental arithmetic skills [LO 1.9]

To examine and extend numeric patterns [LO 2.1]

1. It happens often that one has to think quickly. That is why mental arithmetic skills are very important. Let us see whether you can work faster than your friend. Work in pairs and see who can give the answer first. Start at the arrow every time and work clockwise.

Figure 1
Figure 1 (graphics1.png)

DO YOU STILL REMEMBER?

Rows of numbers sometimes provide very interesting patterns. If we, for instance, begin at 350 and keep adding 15, we'll get the following pattern:

350 ; 365 ; 380 ; 395 ; 410

2. Rows of numbers always have some sort of numeric pattern. Examine the following patterns and see whether you can complete the rows correctly (use your pocket calculator, if necessary, to check that you have worked correctly):

2.1 495 ; 503 ; 511 ; _________ ; _________ ; . _________ ; _________

2.2 870 ; 855 ; 840 ; _________ ; . _________ ; . _________ ; _________

2.3 3 752 ; 3 761 ; _________ ; _________ ; 3 788 ; _________ ; _______

2.4 _________ ; _________ ; 9 720 ; 9 680 : _________ ; _________

3. In our everyday life it is very important to be able to read and say numbers correctly. We also need to know which number is greater/smaller than the other. Just think of the number of times per day you work with money. If you save R220, for instance, you would certainly not want R202 to be written in your savings booklet! Look at the following numbers and write them down in order from the GREATEST to the SMALLEST (descending order).

3.1 303 ; 330 ; 333 ; 33 ; 3 003

_____________________________________________________________________

_____________________________________________________________________

3.2 6 006 ; 6 600 ; 6 666 ; 6 060 ; 6 606

_____________________________________________________________________

_____________________________________________________________________

Assessment

Learning Outcome 1: The learner will be able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems.

Assessment Standard 1.9: We know this when the learner performs mental calculations;

Learning Outcome 2: The learner will be able to recognise, describe and represent patterns and relationships, as well as to solve problems using algebraic language and skills.

Assessment Standard 2.1: We know this when the learner investigates and extends numeric and geometric patterns looking for a relationship or rules, including patterns.

Collection Navigation

Content actions

Download:

Collection as:

PDF | EPUB (?)

What is an EPUB file?

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

Downloading to a reading device

For detailed instructions on how to download this content's EPUB to your specific device, click the "(?)" link.

| More downloads ...

Module as:

PDF | More downloads ...

Add:

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? tag icon

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? tag icon

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