7th Grade Math

Multiply and Divide Integers

PART A B CD

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 0706.1.3, GLE 0706.1.8,

GLE 0706.2.2.

102 Integers

Main Idea

Model multiplication

and division of integers.

Multiply and Divide Integers

SCHOOL The number of students who bring their lunch to Phoenix

Middle School has been decreasing at a rate of 4 students per month.

What integer represents the total change after three months?

What do you need to find? the total change in the number of

students who bring their lunch to school

The integer -4 represents a decrease of 4 students each month.

After three months, the total change will be 3 × (-4). Use

counters to model 3 groups of 4 negative counters.

Place 3 sets of 4 negative counters on the mat.

Count the number of negative counters.

The integer -12 represents the total change in the number of

students who bring their lunch to school.

If the first factor is negative, you will need to remove counters from

the mat.

Use counters to find - 2 × (-4).

The expression - 2 × (-4) means to remove 2 sets of

4 negative counters.

Place 2 sets of 4 zero pairs on the mat.

+ + + +

   - - - -

   + + + +

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