Order of operations

• Math
• 5th Grade

Order of operations

What is order of operations?

This is an equation with more than one operation (addition, subtraction, multiplication, and division):

21 ÷ (5 + 2) x 22 - 10

How do we know what to do first? 

The order of operations is a list of rules about what part of the equation to do first.

Order of Operations:

1. Do operations in parentheses.
2. Simplify exponents.
3. Multiply and divide from left to right.
4. Add and subtract from left to right.

For example:

21 ÷ (5 + 2) x 22 - 10

Step 1:  = 21 ÷ 7 x 22 - 10

Step 2:  = 21 ÷ 7 x 4 - 10

Step 3:  = 12 - 10

Step 4:  = 2

"Please Excuse My Dear Aunt Sally" is a mnemonic to help remember the order of operations.

(Remember that there are four steps - not six!)

In this equation, what should you do first?
10 x (16 - 11) + 2 = ?

1. Multiply 10 x 16
2. Solve inside the parentheses (16 - 11)
3. Multiply 10 x (-11)
4. Add 11 + 2

Put the steps in the correct order:

1.

2.

3.

4.

Add and subtract from left to right.

Simplify exponents.

Do operations in parentheses.

Multiply and divide from left to right.

Let's give it a go! Solve this equation:

10 x (16 - 11) + 2 = ?

1. 151
2. 147
3. 30
4. 52

Solve this equation:

70 ÷ 10 + 3² - (4 x 2) = ?

1. 8
2. 18
3. 24
4. 4

How confident do you feel using order of operations?

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