Multiplying integers

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Multiplying integers By Rose Eisenmenger

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Multiplying integers. By Rose Eisenmenger. What Is Multiplication?. A number of groups of a number Example: 6 x 3 is the same as saying 6 groups of 3 This could be shown as:. What Is Multiplication?. - PowerPoint PPT Presentation

Transcript of Multiplying integers

Multiplying integers By Rose Eisenmenger

What Is Multiplication?

A number of groups of a number Example: 6 x 3 is the same as saying 6 groups

of 3 This could be shown as:

What Is Multiplication?

It could also be said in a word problem, Mary had 5 friends coming over, and she wanted each person, including herself, to have 3 chocolates. How many chocolates would she need to buy?

Therefore, multiplication can be shown as: an equation

6 x 3 word problem

Mary had 5 friends … picture

Example 1 Multiplying A Positive By A Negative

Let’s try another problem using equation, word problem, and a picture

Equation 6 x -4

Word Problem Suzie owed 6 of her friends 4 dollars. How

much money did she owe?

Example 1Positive x Negative Picture

Here are 6 boxes of 4, but we need six boxes of negative four

Another way to say negative is, the opposite of, so we need the opposite of 4

4 4 4 4 4 4

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

*Since we are doing the opposite of 6 x 4 which equals 24, our product will be the opposite! What do you think the answer is?-24

Example 2Multiplying A Negative By A

Positive We will also use an equation, word

problem, and picture for this problem Equation

-8 x 5 Word Problem

8 people got a letter in the mail from the bank stating that they received 5$. One week later, the same eight people got another letter saying that the bank made a mistake and meant to say that they owed the bank 5$.

Example 2Negative x Positive Picture

Here are 8 boxes of 5, but we need negative 8 boxes of 5

Another way to say negative is, the opposite of, so we need the opposite of 8 boxes

Since we are doing the opposite of 8 x 5 where we would get a positive answer, we will get an negative product. What do you think the answer is?

5 5 5 5 5

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

5 5

Opposite of…

Opposite of…

5

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Example 3Multiplying A Negative By A

Negative Guess what? We are going to use the same

method for this problem too! Equation

-9 x -2 Word Problem

There were many people at the dog park, but only nine of the people brought two dogs each. All 18 of those dogs found a way to escape under a fence, and became lost. The owners of the dogs went home dog-less and felt “negative” or sad. The next day, all the dogs returned home, which made the owners feel positive!

Example 3 Negative x Negative

We have 9 boxes of two, but we need negative nine boxes of negative two.

Another way to say that is…

2 2 2 2 2

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

2 2

Opposite of…

Opposite of…

2 2

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

Opposite of…

*We have one “opposite of” for each negative number per box*Since there are two negative numbers or “Opposite of…” per box, they cancel each other out*Therefore, your answer will be positive*What do you think your answer will be?

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Let’s Try Some!

6 x -7-8 x 4-3 x 5-6 x -1Challenge: -2 x 0

= -42

= -15

=6

= -32

=0

Multiplying Integers Rules

A positive times a negative equals a negative(pxn)

A positive times a positive equals a positive (pxp)

A negative times a negative equals a positive(nxn)

Between the two factors and the product, there should either be 2 negative numbers or zero negative numbers