Order of Operation

1
Order of Operation

• PEMDAS

2

• Most 7th graders can say the little expression to
  help remember the first letter for the correct
  order of operation.

3
PEMDAS

• Please
• Excuse
• My
• Dear
• Aunt
• Sally

4

• But what do these letters really stand for and
  what do they mean?

5
PEMDAS

• Please
• Excuse
• My
• Dear
• Aunt
• Sally

• Parenthesis
• Exponent
• Multiply
• Divide
• Add
• Subtract

6
PEMDAS
Record in notes section.
operations above or below

• Parenthesis
• Exponent
• Multiply
• Divide
• Add
• Subtract

( ) 25 43 32 x () /
7

• Are you supposed to do ALL multiplication before
  you do any division?

No!
8
No!

• Are you supposed to do ALL addition before you do
  any subtraction?

9

• A way to remember

10

• After you have done all parenthesis and exponents

11

• Think of M, D, A and S as a Family riding in a
  car.

12

• Each step ask yourself
• Who is in the car?
• Who is driving?

That is the operation to do next!
13

• M is Mom,
• D is Dad,
• A is Addi and
• S is Sam.

14
No!

• In the average family car does Mom always drive?

15
No!

• In the average family car does Dad always drive?

16

• If you look in the car, how can you tell who is
  driving?

The "Person" on the LEFT.
17

• Well, in our PEMDAS car, if Mom and/or Dad
  are in the car, they are driving.

18
The "Person" on the LEFT.

• Sam and Addi are twins. So how do we know who
  is driving.

19
Lets try it!
Who is in the car?
Who is driving?

• 48 2 5 x 3 4

20

• 48 2 5 x 3 4

48 2
Who is in the car?
Who is driving?
5 x 3 4
24
21
Who is driving?

• 48 2 5 x 3 4

24 5 x 3 4
5 x 3
24 4
15
Who is in the car?
22
Only one so...

• 48 2 5 x 3 4

24 5 x 3 4
24 15 4
24 15
4
9
13
23

• 48 2 5 x 3 4

How about if we... "Do our own thing"?
Let's just go left to right.
24
5 x 3 4
x 3 4
19
57
4
61
24

• 48 2 5 x 3 4

PEMDAS 13
Left to Right 61
Are these equal?
25
How about if we... "Do our own thing"?

• 48 2 5 x 3 4

Incorrect PEMDAS
48 2 4
15
15 4
24
24
19
5
?
?
?
?
P
E
M
D
A
S
26

• 48 2 5 x 3 4

Are these equal?
PEMDAS 13
Left to Right 61
Incorrect PEMDAS 5
27

• So, is Order of Operation important?
• Why do you think so?

28
12 3(7 5)3
What should we do first?
(2)
12 3 3
Now what should we do ?
(8)
12 3
?
?
P
E
M
D
A
S
29
12 3(7 5)3
Who is driving?
(2)
12 3 3
(8)
12 3
Who is in the car?
4
(8)
32
?
?
P
E
M
D
A
S
30
PEMDAS3 x 4 (325)7
What should we do first?
In the ( ) what should you do?
3 x 4 (95)7
What should we do now?
What does 32 mean?
3 x 4 147
31
PEMDAS3 x 4 (325)7
Who is driving?
3 x 4 (95)7
Who is in the car?
3 x 4 147
12
147
2
12
10
32
PEMDAS5(3 2) 5
What should we do first?
5(5) 5
Who is in the car?
255
5
Who is driving?
33
PEMDAS24 (42 1) 3

1. 10 ?
2. 29
3. 13
4. 26 ?

?
34
PEMDAS1 3(16 4) 32

1. 7
2. 12
3. 5
4. 8

?
35
PEMDAS24 (4 1)2 3

1. 21
2. 3
3. 19
4. 13

?
36
PEMDAS(13 5) 2 2 x 4

1. 28
2. 18
3. 0
4. 1

?
37
PEMDAS10 4 52 2

1. 30
2. 175
3. 70
4. 60

?
38
PEMDAS(72 1) 5 x 2

1. 5
2. 20
3. 6
4. 1.5

?
39
PEMDAS3 12 3 x 2

1. 5
2. 10
3. 11
4. 7

?
40
PEMDAS10 (3 2)4 x 7
?

1. 11
2. 32
3. 35
4. 56