Download Multiplication and Division of Rational Numbers

Multiplication and Division of
Rational Numbers
•
a. In the space below, create a word problem that involves integer multiplication. Write an equation
to model the situation.
•
b. Now change the word problem by replacing the integers with non-integer rational numbers
(fractions or decimals), and write the new equation.
•
c. Was the process used to solve the second problem different from the process used to solve the
first? Explain.
•
d. The Rules for Multiplying Rational Numbers are the same as the Rules for Multiplying Integers:
1. ________________________________________________________________________________
2. ________________________________________________________________________________
3. ________________________________________________________________________________
•
a. In one year, Melinda’s parents spend $2,640.90 on cable and internet service. If
they spend the same amount each month, what is the resulting monthly change in
the family’s income?
•
b. The Rules for Dividing Rational Numbers are the same as the Rules for Dividing
Integers:
1 ._______________________________________________________________
2. _______________________________________________________________
3. _______________________________________________________________
Reviewing Multiplication of Fractions
We love multiplying fractions because it is the
easiest operation to perform.
You simply multiply straight across
You will apply the rules for multiplying integers
to the multiplication of fractions
Visually
3
4
·
1
2
Start with one half, keep three fourths of it
There are 8 pieces total, and you are keeping 3 of them.
3
8
−7
8
·
3
4
−2
5
·
9
14
−3
7
·
−6
19
Division of Fractions
• Remember that division can be represented as
multiplication of the reciprocal.
• You will change division into multiplication
−7
8
÷
3
4
−2
5
÷
9
14
−3
7
÷
−6
19
Decimal Expansions
Multiply or divide as normal, and extend the
rules for integer multiplication and division.
-7.4 x 3.2
-8.73 x -4.26
16.45 ÷ -3.2
-18.32 ÷ -3.81