Warm Up

1
Warm Up
Problem of the Day
Lesson Presentation
2
Warm Up Multiply.
1. 15 ? 2
30
2. 12 ? 8
96
3. 9 ? 16
144
4. 6 ? 11
66
5. 8 ? 15
120
3
Problem of the Day The length of three dowels
are 13 inches, 27 inches, and 19 inches. How can
you use the three dowels to mark off a length of
5 inches?
13 19 27
4
Learn to multiply fractions by whole numbers.
5
Recall that multiplication by a whole number can
be represented as repeated addition. For
example, 4 5 5 5 5 5. You can multiply
a whole number by a fraction using the same
method.



6
Multiply numerators
3
__



4
Multiply denominators
7
Additional Example 1A Multiplying Fractions and
Whole Numbers Multiply. Write the answer in
simplest form.
A. 7
Write 7 as a fraction. Multiply numerators and
denominators.



8
Additional Example 1B Multiplying Fractions and
Whole Numbers Multiply. Write the answer in
simplest form.
B. 6
Write 6 as a fraction. Multiply numerators and
denominators.



Write your answer in simplest form.

9
Additional Example 1C Multiplying Fractions and
Whole Numbers Multiply. Write the answer in
simplest form.
C. 8
Write 8 as a fraction. Multiply numerators and
denominators.


or

5
10
Try This Example 1A Multiply. Write the answer
in simplest form.
A. 4
Write 4 as a fraction. Multiply numerators and
denominators.



11
Try This Example 1B Multiply. Write the answer
in simplest form.
B. 3
Write 3 as a fraction. Multiply numerators and
denominators.



Write your answer in simplest form.

12
Try This Example 1C Multiply. Write the answer
in simplest form.
C. 9
Write 9 as a fraction. Multiply numerators and
denominators.


or

6
13
Additional Example 2A Evaluating Fraction
Expression Evaluate 4x for the value of x. Write
the answer in simplest form.
A. x
Write the expression.
4x
4

Substitute for x.
Multiply.


Write your answer in simplest form.

14
Additional Example 2B Evaluating Fraction
Expression Evaluate 4x for the value of x. Write
the answer in simplest form.
B. x
Write the expression.
4x
4

Substitute for x.
Multiply.


Write your answer in simplest form.

,or 1
15
Try This Example 2A Evaluate 3x for the value of
x. Write the answer in simplest form.
A. x
Write the expression.
3x
3

Substitute for x.
Multiply.


Write your answer in simplest form.

16
Try This Example 2B Evaluate 3x for the value of
x. Write the answer in simplest form.
B. x
Write the expression.
3x
3

Substitute for x.
Multiply.


Write your answer in simplest form.

1
17
Sometimes the denominator of an improper fraction
will divide evenly into the numerator. When this
happens, the improper fraction is equivalent to a
whole number, not a mixed number.
This makes sense if you remember that the
fraction bar means divided by.
18
Additional Example 3 Application There are 25
students in the music club. Of those students,
are also in the band. How many music club
students are in the band?
3
__
5
25


15
There are 15 music club students in the band.
19
Try This Example 3 There are 18 saltwater fish
in the aquarium. Of those fish, are blue. How
many fish in the aquarium are blue?
To find of 18, multiply.
18


12
There are 12 blue fish in the aquarium.
20
Lesson Quiz
Multiply. Write each answer in simplest form. 1.
10 2. 6 Evaluate 6x for each value of
x. Write your answer in simplest form. 3. x
4. x 5. Alicia spent 15 minutes making a
pizza. Of those minutes were spent rolling
out the crust. How many minutes did Alicia spend
rolling out the crust?
4
5
5 minutes