MPM 1DI - Principles of Mathematics
Multiplying Integers
Example: - Temperatures below freezing are indicated by negative integers; temperatures above freezing by
positive integers.
In general, numbers such as 1,2,3, ...are called positive integers; and numbers such as -1, -2,-3,... are called
negative integers. The negative integers, zero, and positive integers make up the set of integers, denoted by I.
So, 𝐼 = {… , −3, −2, −1,0,1,2,3, … }.
Integers such as -2 and 2 are called opposite integers.
Integers can be represented on a number line.
Note that any integer on the number line is greater than all the integers to its left and less than all the integers
to its right.
Rules of Multiplication
Rules of Division
Note that the product/quotient of two integers with the same signs is positive, otherwise negative.
Ex 1: Simplify.
a) (-2)(+6)
d) (-3)(-4)(-5)(-1)
b) (-7)(-5)
e) (-6)(-4)(-2)
c) (+9)(-6)
How can you determine the sign the answer when you are multiplying more than two terms?
Ex 2: Simplify.
a)(+63)÷(-9)
b) (-42)÷(-7)
Ex 3: Simplify the following without calculators.
a) 23
b) 7÷131
x5
(−2)(−3)
c) (−4)(−1)(−5)
c) 21
x35
Question: Can you divide any number by zero?
Note that positive integers are usually written without the positive sign.
Pg. 19: #1 acegikmo, 3acegi, 4 acegi
Pg. 23: #1, 2abcde, 3abcde, 4ghi