5 Minute Check
Complete in your notebook.
1.
1
3
x 12
2.
3
7
x 8
3.
5
6
x 15
4.
2
5
x 11
5 Minute Check
Complete in your notebook.
1.
1
3
x 12
5 Minute Check
Complete in your notebook.
1.
1
3
1
3
x 12
x
12
1
=
12
3
= 4
5 Minute Check
Complete in your notebook.
2.
3
7
x 8
5 Minute Check
Complete in your notebook.
2.
3
7
3
7
x 8
x
8
1
=
24
7
= 3
3
7
5 Minute Check
Complete in your notebook.
3.
5
6
x 15
5 Minute Check
Complete in your notebook.
3.
5
6
5
6
x 15
x
15
1
=
60
6
= 10
5 Minute Check
Complete in your notebook.
4.
2
5
x 11
5 Minute Check
Complete in your notebook.
4.
2
5
x 11
2
5
11
1
x
=
22
5
=4
2
5
Flashcards!
Wednesday, Oct 23
Lesson 4.3
Multiply Fractions
Multiply Fractions
Objective: To understand how to multiply
fractions.
Multiply Fractions
At the end of this lesson you should be able
to answer the following question.
If two positive fractions are less than one, why
is the product also less than one?
Multiply Fractions
To multiply fractions, multiply the numerators
and multiply the denominators, then simplify if
needed.
Example x
=
3
2
6
4
5
20
x
=
x
=
=
3
10
Multiply Fractions
Multiply.
1
2
x
3
5
=
Estimate?
Reminder – When estimating the product of
two fractions, round each fraction to 0, ½ or
1 and then multiply.
Multiply Fractions
Multiply.
1
2
1
2
x
3
5
1
2
=
x =
1
4
Actual Product?
Multiply Fractions
Multiply.
1
2
x
3
5
=
Actual Product?
1
2
x
3
5
=
3
10
Is this a reasonable answer?
Multiply Fractions and Whole Numbers
Multiply.
1
2
x
3
5
=
Actual Product?
1
2
x
3
5
=
3
10
3
Is this a reasonable answer? 10
≈
1
4
Multiply Fractions
Multiply.
2
3
x
5
6
=
Do this on your own.
Multiply Fractions
Multiply.
2
3
x
Estimate?
5
6
=
Multiply.
2
3
1
2
x
MuMultiply Fractions
5
6
=
x1=
1
2
Actual Product?
Multiply Fractions
Multiply.
2
3
x
5
6
=
Actual Product?
2
3
x
5
6
=
10
18
=
5
9
Is this a reasonable answer?
Multiply Fractions
Multiply.
2
3
x
5
6
=
Actual Product?
2
3
x
5
6
=
10
18
=
5
9
5
Is this a reasonable answer? 9
≈
1
2
Multiply Fractions
If the numerators and denominators have a
common factor you can simplify before
multiplying.
Multiply Fractions
If the numerators and denominators have a common factor you
can simplify before multiplying.
Example
2
3
x
5
6
=
All numbers are prime factors (which means they
have no factors other than one and itself), except
for 6. What are the factors of 6?
Multiply Fractions
If the numerators and denominators have a common factor you
can simplify before multiplying.
Example
2
3
2
3
x
5
6
x
5
2x3
=
=
Are there any factors that appear
in the numerator and denominator?
Multiply Fractions
If the numerators and denominators have a common factor
you can simplify before multiplying.
Example
2
3
2
3
x
5
6
x
5
2x3
=
=
2 the common to both
Multiply Fractions
If the numerators and denominators have a common factor
you can simplify before multiplying.
Example
2
3
2
3
x
5
6
x
5
2x3
=
=
5
9
We can cancel the both 2’s.
Multiply.
4
9
Multiply Fractions
x 18 =
Do this on your own.
Multiply Fractions
Multiply.
4
9
4
9
x 18 =
x
18
1
4
9
= x
2x9
1
8
1
= =8
Multiply.
3
5
Multiply Fractions
x 10 =
Do this on your own.
Multiply Fractions
Multiply.
3
5
3
5
x 10 =
x
10
1
=
3x2x5
5x1
6
1
= =6
Multiply Fractions
Frank had ½ of the lawn left to mow. On Saturday he
mowed 2/3 of what was left. What fraction of the lawn did
he mow on Saturday?
Do this on your own.
Multiply Fractions
Frank had ½ of the lawn left to mow. On Saturday he
mowed 2/3 of what was left. What fraction of the lawn did
he mow on Saturday?
1
2
x
2
3
=
2
6
=
1
3
Multiply Fractions
A paint store has 35 gallons of paint in storage, 2/5 of
which are for outdoor use. The others are for indoor use.
If each gallon costs $22, what is the total cost of the
indoor paint in storage?
Do this on your own.
Multiply Fractions
A paint store has 35 gallons of paint in storage, 2/5 of
which are for outdoor use. The others are for indoor use.
If each gallon costs $22, what is the total cost of the
indoor paint in storage?
There is a couple of different ways to solve this problem.
If 2/5 is outdoor paint, what fraction is indoor paint?
Multiply Fractions
A paint store has 35 gallons of paint in storage, 2/5 of
which are for outdoor use. The others are for indoor use.
If each gallon costs $22, what is the total cost of the
indoor paint in storage?
If 2/5 is outdoor paint, what fraction is indoor paint? 3/5
What is 3/5 of 35 gallons?
Multiply Fractions
A paint store has 35 gallons of paint in storage, 2/5 of
which are for outdoor use. The others are for indoor use.
If each gallon costs $22, what is the total cost of the
indoor paint in storage?
If 2/5 is outdoor paint, what fraction is indoor paint? 3/5
What is 3/5 of 35 gallons?
3
5
x
35
1
=
105
5
= 21
What is the cost of 21 gallons?
Multiply Fractions
A paint store has 35 gallons of paint in storage, 2/5 of
which are for outdoor use. The others are for indoor use.
If each gallon costs $22, what is the total cost of the
indoor paint in storage?
What is the cost of 21 gallons?
21 x $22 = $462
Multiply Fractions
If two positive fractions are less than one, why
is the product also less than one?
Multiply Fractions
Agenda Notes
Homework –
Homework Practice 4-3
Show all Work
Due Thursday, Oct 24
Mid Chapter 4 Quiz –Monday, Oct 28