# 1Tvwo Ch 9 §9-4 The calculator

What is the main purpose of using the CALCULATOR ?

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Slide 1: Mind map
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This lesson contains 34 slides, with interactive quizzes, text slides and 1 video.

Lesson duration is: 50 min

## Items in this lesson

What is the main purpose of using the CALCULATOR ?

#### Slide 1 -Mind map

John orders Chips and Cola for himself and 6 friends.
Prices: Chips € 2 and Cola € 1.65
How to calculate the total cost?
A
cost = 2 + 1.65 x 7
B
(2 + 1.65) x 7 = cost
C
7 x (2 +1.65) = cost
D
cost = (7 + 1.65) x 2

#### Slide 2 -Quiz

Both prices, 2 € and 1.65 €, have to be multiplied by 7, because all the 7 boys get Cola and Chips.
This is done by putting brackets over 2 + 1.65

#### Slide 3 -Slide

a. 13.5 + 9.2 x 8.3 =
A
89.68
B
89.86
C
98.86
D
98.68

#### Slide 4 -Quiz

6.1 x (3.7 - 5.4) =
A
13.07
B
10,37
C
-10.37
D
-13.07

#### Slide 5 -Quiz

6.5 x 8.2 + 4.8 : 8 =
A
35,9
B
95.3
C
39,5
D
53.9

#### Slide 6 -Quiz

Comment on Task 2, 3 and 4
Calculating these exercises asks precision from you.
Not forgetting anything, for example brackets!
The funny thing is, you do not have to really understand anything about 'order of operations' for this task.
Your sillicone friend, the calculator, takes good care of that!

#### Slide 8 -Video

Write as decimal numbers, using your calculator.
Round to 3 decimal numbers.

4228
A
0.667
B
0,667
C
0.666
D
0,666

#### Slide 9 -Quiz

To write          as a decimal number, rounding to 3 decimal numbers,
you  can do:
- key in:  '28 : 42 =' , followed by rounding,
or: use the 'a  b/c' button, left column, 3rd from above:
- key in:  '28  a  b/c  42 ='. Now you get your answer as a fraction!
To change this into a decimal number, key in:  a  b/c.
Finally round again.
4228

#### Slide 10 -Slide

Do the same with:
6
97
A
7.668
B
6.887
C
6.778
D
8.667

#### Slide 11 -Quiz

How to key in:    6       ?
Two ways:
-        6 + 7 : 9 =        , or:
-         6  a b/c   7  a b/c  9  =
Now you get the answer as a fraction. To change this to a decimal number, key in: a  b/c.

97

#### Slide 12 -Slide

Do the same with:
39
5147
A
93.922
B
39,922
C
92.229
D
39.922

#### Slide 13 -Quiz

Calculate and round to whole numbers:

8842 x
135
A
3400
B
3401
C
340.1
D
34.1

#### Slide 14 -Quiz

Instruction A :
How to solve an equation and round the answer?
Example:
Solve this equation:
47c - 38 = -7 (place a card on 47c)
47c = 31
c =
c        0.660
For this notation, see next slide!
4731

#### Slide 15 -Slide

N  Notation of an approximation:
Instruction B:
The solution
is written as a decimal number as follows:                    0.660
This number is rounded to 3 decimal places.
The symbol         means 'is approximately equal to' and indicates that it is a rounded number.
4731
4731

#### Slide 16 -Slide

Solve and round the following equation on paper:
17 + 16x = 40
A
1.44
B
1.438
C
1,44
D
14.4

#### Slide 17 -Quiz

Solve this equation:
17 + 16 x = 40
16 x = 23
x =
Rounded to three decimal places  x      1.438
1623

#### Slide 18 -Slide

Solve the following equation on paper:
-9v + 19 = 32
Use this sign, which means 'is approximately equal to':

A
1.44
B
-1.444
C
-1.445
D
1,444

a. -9v + 19 =32
-9v = 13
v =
v      -1.444
913

#### Slide 20 -Slide

HOMEWORK
From now on, some homework exercises appear.
If you keyed in the wrong answer, try again!
You have the choice between:
- doing extra basic exercises (purple circle), for the BLUE group (needing more help)
- doing more challenging exercises (yellow circle), for the GREEN and PURPLE group
- doing both types of exercises (purple and yellow circles),
but remember: do at least half of all exercises!
Maybe you even do all of them.

#### Slide 21 -Slide

Extra BASIC:
0.5 + (4.6 + 12.4 ) : 34 =
A
2
B
1
C
0
D
3

#### Slide 22 -Quiz

Etra Basic:
Calculate:
(24.9 - 12.5) x 8.8 - 10.4 =
A
89.72
B
98,72
C
98.72
D
97.72

#### Slide 23 -Quiz

Which numbers(s) cannot be written as a decimal number that has exactly the same meaning?

41
32
65
54
A
2/3 only
B
1/4 and 5/6
C
5/6 and 4/5
D
2/3 and 5/6

#### Slide 24 -Quiz

Task 14: Extra Basic: Calculate and round to 2 decimal places:
477 x
74
A
272,57
B
227.57
C
272.57
D
227.571

#### Slide 25 -Quiz

Solve this equation on paper.
Use the card method.

47c - 38 = -7
A
0.660
B
0.661
C
0.659
D
0,660

#### Slide 26 -Quiz

CHALLENGE:
Make an equation for the following information:

27 Players of a football club will be taken to their match.
5 Of them always travel with their coach in his car.
There is room for 3 players in each of the cars of the parents.
Call the number of parents n.
Which of the following equations is correct?
A
27 = 4n + 5
B
5n + 3 = 27
C
5 + 3n = 27
D
27 = 5n + 3

#### Slide 27 -Quiz

CHALLENGE:
Solve the equation from the previous slide:
5 + 3n = 27
So: calculate n, the number of parents.
This number has to be rounded sensibly!
A
n = 7.333
B
n = 7
C
n = 7 .3
D
n = 8

#### Slide 28 -Quiz

Extra Basic
Solve this equation on paper.
2388 = 2000x + 387
A
1.0005
B
1,002
C
1.001
D
-1.001

#### Slide 29 -Quiz

Extra Basic:
Solve this equation on paper.
Finally key in the answer, rounded to 3 decimal places:
123 = 23e - 3

A
5.47
B
5.48
C
5,48
D
5.478

#### Slide 30 -Quiz

Dear boys and girls, this was the final 'extra exercise'.
There is one more 'challenge exercise' to come.
Hope you learned a lot and enjoyd too!

#### Slide 31 -Slide

CHALLENGE:
In 2008 a world record was set for the fastest journey around the world in a speed boat. It lasted 1663.82 hours.
Calculate this in days, hours and minutes. Round to whole minutes.
A
99,829.2 minutes
B
69 days, 7 hours and 49 minutes
C
69 days, 7 hours and 53 minutes
D
69 days, 7 hours and 54 minutes

#### Slide 32 -Quiz

Dear boys and girls, the task you've just been doing was the final homework exercise!
Hope you learned a lot and enjoyed!

#### Slide 33 -Slide

Homework time
Do §10-4 The calculator now,
afterwards checking your results with the
Solutionbook.