1. Multiplying and Dividing Integers
Sec 2.4 & 2.5

2. Multiplying Integers Let’s multiply! 8(3) = 24
What about when we have negative numbers?
-4(-8) =
Well, 4(8) = 32 as always, but what do we do about the sign?
When multiplying
The product of two integers with the same sign is positive, so…
-4(-8) = 32

3. Multiplying Integers
9 * 20 =
180
-5 * -12 = 60
(-10)(-34) =
340
But what happens when the signs are different?
The product of two integers with different signs is negative.
(-5)(7) =
-35

4. Multiplying Integers -8 * 11 = -88 -12 * 4 = -48 (-7)(9) = -63
(-6)(-7) = 42

5. Multiplying Integers
Every month, the school loses 40 pencils. How many will it lose in a year?
Write an expression for the above problem and solve it.
There are 9 months in a school year, so
9 * 40 pencils = 360 pencils

6. Dividing Integers
Division and multiplication are related. The rules for signs in integers work the same.
The quotient of two integers with different signs is negative.
Dividend ÷ Divisor = Quotient
12 ÷ -2 = -6
The quotient of two integers with the same signs is positive.
(-65) ÷ (-5) = 13

7. Multiplying and Dividing Integers
(-9) ÷ 3 = -3
(-11)(-12)
132
200 ÷ - 20 =
-10
7 * (-3) =
-21
(-81) ÷ (-3) = 27