Multiplying and Dividing Integers

At this stage, multiplying and dividing numbers is an easy

task.

When we introduce positive and negative signs, a series of rules are needed.

This is where we begin today

8 X 9 = 15 5 =72 3

Positive Positive(+7) X (+3) =

(+21)

(+3) X (+8) = (+24)

With all positives, we can drop the brackets and signs

7 X 2 = 14

Positive Negative

(+3) X (-4) =

(-12)

3 peopleDebt of four dollars

Suppose you borrow $4.00 off of three different people. How much are you in debt?

Total debt: 12 dollars

(+3) X (-4) = (-12)

(-5) X (+8) = (-40)

Multiplying 2 integers with different signs gives a negative number.

Negative Negative

(-3) X (-5) =

(+15)

(-2) X (-5) = (+10)

WHY?……….

“two negatives make a positive”

WHY?

Consider spending money…Suppose you spend $10.00 a

week on junk food….

How much money have you

spent since 3 weeks ago?

(-10) X (-3) =

(Spend $10.00) X (3 weeks ago) =

(+30)

You have spent 30 dollars

(-7) X (-4) = (+28)

(-2) X (-8) = (+16)

Try these:

The rules for multiplication apply to the process of division as well…

See Sheet