Math 7 ( Period 4)

Multiplying and Dividing Integers 3.5 & 3.6

They have the same rules! (The rules are different from adding and subtracting integers… so keep these straight!)

Textbook Rules:
If you have 2 signs that are the SAME, the product or quotient is POSTIIVE

IF you have 2 signs that are DIFFERENT, the product or quotient is NEGATIVE

Good Guy/ Bad Guy Rules… or Life’s Lessons…

Good thing happens to Good person à that’s Good

Bad thing happens to a Good Personà that’s Bad (That’s not right! We hate when that happens)

Good thing happens to a Bad person à That’s Bad (We hate when good things happen to people who don’t deserve it.

Bad thing happens to a Bad person à that’s good (That’s Karma … they got what they deserved)

+ ∙ + = +

- ∙ + = -

+ ∙ - = -

-  ∙ - = +

It works with division as well!

Finger Rules:

If your index finger represents the negative sign then if  you have two negatives you have the index fingers of both your left hand and your right hand and they make a plus sign!

If you have just one negative it just stays negative because you don’t have another finger to cross it

If you have more than two negatives you just keep using your index fingers to determine the sign.

We did this in class. It’s fun… but once you get it.. you won’t need to keep doing it ( unless you want to keep having fun!)

What if there are more than 2 signs?

Use Aunt Sally’s  Rules (O³) and go left to right

or be a Sign Counter

…an ODD number of negatives = Negative

…an EVEN number of negatives = Positive

Only count the negative signs… you do not worry about how many numbers are involved nor the positives… only count the Negatives

(-2)(-5)(-3) = -30 (there are 3 negatives—and 3 is odd)

(2)(-5)(-3) = +30 (there are 2 negatives and 2 is an even number)

(2)(5)(-3) = -30 (there is only 1 negative and that is odd!)