1TH/Vwo §7.3 Decimal numbers

§7.3 Decimal numbers
You all know about decimal numbers.
It is similar to fractions, but now written with a point and not with a fraction symbol.
So:   0.5    instead of   
21
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Slide 1: Slide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

This lesson contains 20 slides, with interactive quizzes and text slides.

time-iconLesson duration is: 30 min

Items in this lesson

§7.3 Decimal numbers
You all know about decimal numbers.
It is similar to fractions, but now written with a point and not with a fraction symbol.
So:   0.5    instead of   
21

Slide 1 - Slide

The same 'order of operations' as you learnt applies now!
And you can take the
+ sum.              ( 5 + 6 = 11)
+ difference   ( 8 - 5 = 3 )
+ product        ( 4 x 5 = 20 )
+ quotient        ( 49 : 7 = 7 )                                       again!
+ above all the brackets 'rule' again, having top priority!

Slide 2 - Slide

The same 'order of operations' as you learnt applies,
also with decimal numbers included!

Slide 3 - Slide

Slide 4 - Slide

Slide 5 - Slide

8 - 4 x 1.5 =
timer
0:30
A
6
B
18
C
-2
D
2

Slide 6 - Quiz

explanation:
First comes X  and only then we do  -,  so:

8 - 4 x 1.5 =
8 - 6 = 2

Slide 7 - Slide

0.01 x 2000 = ...
A
200
B
20
C
200000
D
20000

Slide 8 - Quiz

Slide 9 - Slide

Realize that:
When the decimal point goes
- to the right, then the number gets greater, for example:
    10 x 0.03 = 0.3     or     100 x 0.003 = 0.03            or.    300 x 0.002 = 0.6
- to the left, then the number gets smaller, for example:
     0.01 x 240.8 = 2.408      or.  0.003 x 2222.2 = 6.6666
The next slide summarizes all this!

Slide 10 - Slide

Slide 11 - Slide

Slide 12 - Slide

5.6 x 0.01 = ....
A
5600
B
0.56
C
0.056
D
560

Slide 13 - Quiz

explanation:
multiplying by 0.01 is the same as taking 
of that number, or placing the decimal point 2 places to the left, so:
5.6 x 0.01 = 0.056
 
1001

Slide 14 - Slide

Finally a remark about exercise 25:
In 25 the calculations have become that complicated, that it is important to work them out in a few steps!
Look at the following example.

Slide 15 - Slide

This becomes pretty tricky, reason for us to work it out on paper like this:
0.1 x 14 x 100 =
 1.4 x 100 = 140
So first the brackets, then the square and finally the 2 multiplications!
When doing exercise 25 in a few minutes, make such calculations!!

Slide 16 - Slide

One more TASK: a FOTOVRAAG!

      4.2 + (      - 28) =
+ Copy this task in your Notebook
+ write down the CALCULATION and only then the ANSWER
+ take a picture and 
+ send it in in the FOTOVRAAG!

82

Slide 17 - Slide

VWO task
Send in a pic of your CALCULATION!


4.2+(8228)=
timer
2:00

Slide 18 - Open question

Explanation:
4.2 + (      - 28)  =               Brackets first.
4.2 + (64 - 28) =               Between the brackets: the power first.
4.2 + 36  =   
40.2                        


82

Slide 19 - Slide

Homework time
do § 7.3 now 
you may skip:  18  and  19
however, don't forget to WORK OUT exercise 25, so don't 
only give the answers!

Slide 20 - Slide