7th Grade Math

Multiply and Divide Integers

PART A B C D

Multi-Part

Lesson 3

Get ConnectED

GLE 0706.2.1

Extend understandings of

addition, subtraction,

multiplication and division

to integers. SPI 0706.2.5

Solve contextual problems

that involve operations with

integers. Also addresses

GLE 0706.1.4, GLE 0706.2.2,

SPI 0706.2.1.

104 Integers

Main Idea

Multiply integers. Multiply Integers

COOKING Genevieve’s freezer

decreases the temperature of a piece of pie

by 3° every minute. What is the change

in degrees after 4 minutes?

1. Write a multiplication sentence to
   represent the situation above.


2. How could you model the multiplication
   sentence above with counters?

Remember that multiplication is the same as repeated addition.

4 (-3)^ = (-3)^ + (-3)^ + (-3)^ + (-3) -3 is used as an addend four times.

= - 12

• 12 - 11 - 10 - 9 - 8 - 7 - 6 - 5 - 4 - 3 - 2 - 101
  
  
  • 3 - 3 - 3 - 3
  
  
  
  

The Commutative Property of Multiplication states that you can

multiply in any order. So, 4(-3)^ = - 3(4).

Multiply Integers with Different Signs

Words The product of two integers with different signs is negative.

Examples 6(-4)^ = - 24 - 5(7)^ = - 35

Multiply Integers with Different Signs

Find 3(-5).

3(-5) = - 15 The integers have different signs. The product is negative.

Find -6(8).

• 6(8)^ = - 48 The integers have different signs. The product is negative.

a. 9(-2) b. -7(4)

decrea

102_113_C2L3_895130.indd 104 12/29/09 12:50 PM