Download 2.2 Multiplying a Whole Number by a Fraction and Vice Versa When

2.2 Multiplying a Whole Number by a Fraction and Vice Versa
When we first learned to multiply numbers we thought of them as repeated
multiplication.
Example: 2 x 3 = 3 + 3 = 6
When we multiply a whole number by a fraction we can also think of it as
repeated addition.
Example:
a) 2 x
1
=
4
b) 2 x
1
=
3
c) 2 x
1
=
5
When we multiply a fraction by a whole number or vice versa we multiply the
whole number by the numerator of the fraction and place the product over
the denominator.
Example:
a) 3 x
b) 6 x
c) 2 x
2
3x 2
6
=
=
which is an improper fraction and we
3
2
3
can change this fraction to 2.
1
6x1
6
=
=
12
12
12
3
2x3
6
=
=
which can be changed to
4
4
4
a mixed number.
HOMEWORK: WORKSHEET ATTACHED
Fraction by a Whole Number worksheet
1. Multiply. Include a diagram for each:
a) 16 x
1
4
b) 12 x
1
3
c) 10 x
1
5
d) 6 x
5
6
2. Two products are given. Which is greater?
a) 2 x
1
1
OR 4 x
3
8
b) 2 x
3
5
c) 3 x
1
1
OR 4 x
2
2
OR 4 x
2
3
3. Multiply the following: (Use a diagram if needed)
1
2
a) 6 x
2
3
b) 12 x
c) 9 x
1
5
d)
2
x 10
5
e)
1
x3
6
f) 7 x
1
2
g) 2 x
4
9
h)
1
x4
4
i) 8 x
2
12
Word Problems
When reading word problems we can think of the word “of” in some cases
as meaning multiply.
Example 1:
Nancy’s class has 24 students. She conducts a survey and find
1
that
of the class wears glasses. How many students in the class wear
3
glasses?
Answer:
Sometimes word problems won’t have the “of” to help you/
Example 2:
1
of an hour to change in or out of his
6
soccer gear. If he usually plays soccer twice a week, how many hours
does he spend changing per week? Per month?
Marty takes about
Answer:
HOMEWORK: Page 74 #9 to #13