1. Warm Up Problem
A class has 6 boys and 15 girls. What is the ratio of boys to girls? Explain the meaning of the ratio.

2. Numerical Expressions
Lesson 6-2

3. Objectives
I can find the value of expressions using the order of operations.
I can memorize the steps of the order of operations.

4. Vocabulary
numerical expression – a combination of numbers and operations
Example: 3 x x 4
order of operations – tells you which operation to perform first, so that everyone finds the same value for an expression

5. Order of Operations - Notes
PEMDAS or Please Excuse My Dear Aunt Sally
1) Simplify anything inside parentheses.
2) Evaluate the exponents.
3) Multiply and divide in order from left to right.
4) Add and subtract in order from left to right.

6. Example 1
Find the value of the numerical expression. 10 – Use an ice cream cone! 1. There are no parentheses or exponents. 2. There are no multiplication or division symbols. 3. Add and subtract from left to right. 10 – 2 = = 16

7. Example 2
Find the value of the numerical expression x 5 Use an ice cream cone! 1. There are no parentheses or exponents. 2. Multiply first. 3 x 5 = Then add: = 19

8. Got It? Evaluate each expression. Use an ice cream cone!

9. Example 3
Find the value of the numerical expression. 20 ÷ x (9 – 6) Use an ice cream cone! 1. Solve inside the parentheses first. 20 ÷ 4+17 x 3 2. There are no exponents.

10. Example 3
Find the value of the numerical expression. 20 ÷ x (9 – 6) Use an ice cream cone! 3. Divide and multiply left to right. 20 ÷ x 3 = x x 3 = Add and subtract left to right = 56

11. Example 4
3 x 𝟔 𝟐 + 4 Use an ice cream cone! 1. There are no parentheses. 2. Simplify the exponent first. 3 x = 3 x Multiply. 36 x 3 = Add = 112

12. Example 5 5 + ( 𝟖 𝟐 -2) x 2 Use an ice cream cone!
1. Because the exponent is inside the parentheses, simplify the exponent first.
5 + ( ) x 2
= 5 + (64 – 2) x 2
2. Then solve (64-2).
= x 2
3. Multiply.
x 2
4. Add.
= 129

13. Got It? Evaluate each expression. Use an ice cream cone!
4) 24 ÷ ( )
5) 22 ÷ 2 x 3 2

14. Example 6
Write an expression for the total cost of 5 candies, 2 candles, and 4 lip balms. Find the total cost.
5 x $5 + 2 x $7 + 4 x $2
= x x 2
= x 2 =
= $47
Cost of Items
Item
Candies
Candle
Lip balm
Cost $) 5 7 2

15. Got it?
6) Alexis and 3 friends are at the mall. Each person buys a pretzel for $4, sauce for $1, and a drink for $2. Write an expression for the total and find the total cost.