Order of OperationsOrder of Operations

By Mr. WalkerBy Mr. Walker

The ExpressionThe ExpressionWe need to simplify this expression down to one number (find the answer).

But where do we start?

There is a certain order we need to follow when we simplify this expression, or we will get the wrong answer. This is called…

Order of Operations

It goes like this… Going left to right (like when reading)• Do anything in Parentheses• Start over and do any Exponents• Start over and do any Multiplication and Division• Start over and do any Addition and Subtraction

+(3x5)-2325

5

DefinitionsDefinitions

+(3x5)-2325

5Parentheses are…

Exponents are … Powers and Roots 2 16

In this problem 2 has a power of three, which means you should multiply 2 by itself three times: 2x2x2

Multiplication and Division are …

( )

X

is the same as saying 25 5255

Addition and Subtraction are… + -

3

How Do I Remember All This?How Do I Remember All This?

Easy… Please Excuse My Dear Aunt Sally

Parentheses

Exponents

Mu l t i p l i ca t on

Division

Addi t ion

Subtract ion

Dear Aunt Sally had a very bad day, so please excuse her.It all started when she burnt her tongue on her hot coffee.Then on the way to work her car died. While she was walking the rest of the way to work a car drove by and splattered her with mud. When she finally got to work her boss fired her for being late. Since she did not have a job anymore she started walking home and found a quarter on the sidewalk near a tree. ‘Great,’ she thought but soon found out that it was super-glued to the sidewalk. While she was looking down at the quarter a bee stung her and she stood up so fast that she forgot the tree branch right above her head. BONK! Just then a 7 year old boy bumped into her because he was reading a comic book as he walked.When he looked up to say ‘Excuse me,’ this is what he saw…

So … Please Excuse My Dear Aunt Sally

Step by Step ‘P’Step by Step ‘P’

+(3x5)-2325

5

Please Excuse My Dear Aunt Sally

Parentheses

(3x5) is 15, so put the 15 in the spot of the (3x5)

+15-2325

5

Step by Step ‘E’Step by Step ‘E’

Please Excuse My Dear Aunt Sally

Exponents

+15-2325

5

2 Is the same as 2x2x2

2x2=4 x2 again is 8

So replace the 2 with the 8

3

3

+15-8255

You most likely will not have to deal with this step in 4th grade.

Step by Step ‘M’ & ‘D’Step by Step ‘M’ & ‘D’

Please Excuse (My Dear) Aunt Sally

Mu l t i p l i ca t on

+15-8255

There is nothing to multiply so do the division.

Division

+15-8255

is the same as saying 25 5255

25 divided by 5 is 5.

So replace the with the 5255

5+15-8

Do any multiplication and division as you read left to right

Step by Step ‘A’ & ‘S’Step by Step ‘A’ & ‘S’

Please Excuse My Dear (Aunt Sally)

Addi t ion

5+15-8

Add the 5+15 to get 20

Take out the 5+15 and put the 20 in that spot

20-8

Subtract ion

Subtract the 8 from the 20 and get 12

20- 812

1 10

Take away the 20-8 and put the 12

borrow

Do any addition and subtraction as you read left to right

12 You are done!

Let’s Try One TogetherLet’s Try One TogetherRemember Please Excuse My Dear Aunt Sally

366

5+(3x4)-

Parentheses: (3x4) = 12

Exponents: None-Skip

Multiplication: None-Skip

Division: 36 divided by 6 = 6

Addition: 5+12=17

Subtraction: 17-6=11

366

5+12-

366

5+12-

366

5+12-

5+12-6

17-6

11

Simplify this expression

Try These On Your OwnTry These On Your Own

505

2+(4x9)-

Answer 28

4x(1+7)-24 3

Answer 24

567 +2x(3x9)-60

Answer 2

459

3 -20+( +5)-7

Answer 10

3

For Fun Make Up Your Own Aunt For Fun Make Up Your Own Aunt Sally StorySally Story

Please Excuse My Dear Aunt Sally because…