Saxon Algebra 1/2 Lesson 18 Multiplying Fractions and Whole Numbers, Fractional Part of a Number

1. Measurement
Multiplying Fractions by
Whole Numbers

2. Many problems require the
multiplication of whole numbers by a
fraction.
Multiplying Fractions &
Whole Numbers
Example: Five packages of
cookies are each ¾ full.
How many full packages would
this be if they were combined?

3.  We can use several strategies to solve this
problem:
Multiplying Fractions &
Whole Numbers
5 x ¾ =
= 15/4 or 3 ¾
By counting the number of quarters (1/4) blocks
colored, we can determine the answer.

4. Or, we can use a number line.
Multiplying and Dividing
Fractions
0 1 2 3 4
1 2 3 4 5
Answer: 5 x ¾ = 15/4 or 3 ¾

5. Another option: We can change the
whole number to a fraction and
multiply:
Multiplying Fractions &
Whole Numbers
5 x
3
4
?
?
=

6. We can change the whole number to
a fraction and multiply:
Multiplying Fractions &
Whole Numbers
x
3
4
?
?
=
5
1

7. We can now multiply the fraction:
Multiplying Fractions &
Whole Numbers
x
3
4
?
?
=
5
1

8. The answer is in fraction form.
Multiplying Fractions &
Whole Numbers
x
3
4
15
4
=
5
1

9. This can be transformed into a mixed
number.
Multiplying Fractions &
Whole Numbers
x
3
4
3 ¾
=
5
1

10. Or, we can use the following process
to multiply directly:
Multiply the whole number by the
numerator
Multiplying Fractions &
Whole Numbers
5 x
3
4
?
?
=
x
=

11. The answer is the new numerator.
Multiplying Fractions &
Whole Numbers
5 x
3
4
15
?
=
x
=

12. The denominator remains the same
as the denominator of the fraction.
Multiplying Fractions &
Whole Numbers
5 x
3
4
15
?
=

13. This gives the answer in a fraction
form.
Multiplying Fractions &
Whole Numbers
5 x
3
4
15
4
=

14. This gives the answer in a fraction
form.
Multiplying Fractions &
Whole Numbers
5 x
3
4
15
4
=

15. This can then be transformed into a
mixed number.
Multiplying Fractions &
Whole Numbers
5 x
3
4
3 ¾
=