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# INTEGERS AND MULTIPLICATION - PowerPoint PPT Presentation

INTEGERS AND MULTIPLICATION. The University of Texas at Dallas. MULTIPLICATION. Red and yellow tiles can be used to model multiplication. Remember that multiplication can be described as repeated addition. So 2 x 3 = ?. 2 groups of 3 tiles = 6 tiles. The University of Texas at Dallas.

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### INTEGERS AND MULTIPLICATION

The University of Texas at Dallas

• Red and yellow tiles can be used to model multiplication.

• Remember that multiplication can be described as repeated addition.

• So 2 x 3 = ?

2 groups of 3 tiles = 6 tiles

The University of Texas at Dallas

• 2 x -3 means 2 groups of -3

2 x -3 = -6

The University of Texas at Dallas

• Since 2 x 3 = 6 and 3 x 2 = 6, does it make sense that -3 x 2 = -6 ?

• -3 x 2 = -6 is true.

• +2 x -3 = -6 and -3 x +2 = -6 belong to a fact family:

• Write the fact family on comp book page_____

+2 x -3 = -6

-3 x +2 = -6

-6 ÷ +2 = -3

-6 ÷-3 = +2

The University of Texas at Dallas

• Use your tiles to model each multiplication problem.

• +2 x +4 = ?

2 groups of +4

+2 x +4 = +8

The University of Texas at Dallas

• +3 x -3 = ?

3 groups of -3

+3 x -3 = -9

The University of Texas at Dallas

• -2 x +4 = ?

4 groups of -2

-2 x +4 = -8

• Use the fact family for

• -2 x +4 = ?  We can’t show -2 groups of +4

• +4 x -2 = ? we can show 4 groups of -2

The University of Texas at Dallas

• +1, -1 are opposites

the products are opposite

• Since +2 and -2 are opposites of each other,

• +2 x -3 and -2 x -3 have opposite products.

+1 x +3 = +3

-1 x +3 = -3

The University of Texas at Dallas

• To model -2 x -3 use 2 groups of the opposite of -3

-2 x -3 = +6

The University of Texas at Dallas

• Use tiles to illustrate -3 x -4 =?

3 groups of +4 (the opposite of -4)

-3 x -4 = +12

The University of Texas at Dallas

### What do you notice about multiplying integers???

On comp book page ____ write a few sentences about what you noticed.

### INTEGERS AND DIVISION

The University of Texas at Dallas

• Use tiles to model +12 ÷ +3 = ?

4 yellow tiles in each group.

Divide 12 yellow tiles into 3 equal groups

+12 ÷+3 = +4

The University of Texas at Dallas

• Use tiles to model -15 ÷ +5 =?

Divide -15 into 5 equal groups

-15 ÷+5 = -3

The University of Texas at Dallas

• Write the fact family

• -4 x +2 = -8

• +2 x -4 = -8

• -8 ÷ +2 = -4

• -8 ÷ -4 = +2

The University of Texas at Dallas

-12 divided into 6 equal groups

7) -12 ÷+6

= -2

8) -8 ÷+2

= -4

-8 divided into 2 equal groups

The University of Texas at Dallas

### What do you notice about dividing integers???

On comp book page ____ write a few sentences about what you noticed.

### SUMMARYOn comp book page

The product or quotient of two integers with different signs is negative.

The product or quotient of two integers with the same sign is positive.