1TTO 8.3 Decimal numbers PTI

• mathematics
• Middelbare school
• havo, vwo
• Leerjaar 1

8.3 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   

​2​​1​​

The same 'order of operations' as you learnt applies now!

And you can take the

+ sum

+ difference

+ product and 

+ quotient  again!

+ above all the brackets 'rule' again, having top priority!

6.6 - 4 x 1.5 =

1. 6
2. 3.9
3. -0.6
4. 0.6

explanation:

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

6.6 - 4 x 1.5 =

6.6 - 6 = 0.6

5.6 x 0.01 = ....

1. 5600
2. 0.56
3. 0.056
4. 560

explanation:

multiplying by 0.01 is the same as taking 

of that number, or placing the decimal point 2 places to the right, so:

5.6 x 0.01 = 0.056

 

​100​​1​​

Finally a remark about exercise 28:

In 28 the calculations have become that complicated, that it is important to work them out in a few steps!

Look at the following example.

This becomes pretty tricky, reason for us to work it out on paper like this:

In the last task of this LessonUp...

+ work out your CALCULATION on paper

+ take a picture and 

+ send it in in this LessonUp

+ I am counting on all of you to show your work

and not just the ANSWER!

4.2 + ( - 28) : 4 = ......
So send in a pic of your CALCULATION!

8​2​​

Explanation:

4.2 + (      - 28) : 4 =

4.2 + (64 - 28) : 4 =

4.2 + 36 : 4 =

4.2 + 9 = 

13.2

8​2​​

5.7 + ( - ) = .........

5​2​​

4​2​​

Explanation:

5.7 + (        -           ) =

5.7 + (25 - 16) =

5.7 + 9 = 

14.7

5​2​​

4​2​​

Homework time