1.
We have added and subtracted
fractions. In this lesson we will multiply
fractions. When we add and subtract
fractions, we count how many of the
same size parts there are. When we
multiply fractions, the sizes of the parts
change. Consider this multiplication
problem:
How much is one half of one half?
2.
How much is one-half of one-half?
Using a fraction manipulative, we
show one-half of a circle.
To find one- half of one-
half, we divide the half
in half.
Written out the Problem looks
like this:
1 1 1
2 2 4
X =
We see this equals
one- fourth.
3.
What fraction is one half of three
fourths?
Using a fraction manipulative, we
show three fourths of a circle.
To find one half of three
fourths, we divide each
fourth in half.
Since one half of one fourth is one eighth, one half of
three fourths is three eighths. We may also find one
half of three fourths by multiplying.
1 3 3
2 4 8
X =
EXAMPLE 1:
4.
Multiply:
We find two thirds of four fifths by
multiplying.
2 4
3 5
X =
EXAMPLE 2:
2 4 8
3 5 15
X =
Now You’re
Cooking!
5.
3/5
x 1/2
Now that you know how to
multiply fractions, let’s try some
together.
1/3
x 2/3
2/9 3/10
2/3
x 2/3
4/9
1/2
x 2/2
2/4
3/4
x 1/2
3/8
1/2
x 1/3
1/6
1/2
x 1/4
1/8
6.
3/5
x 1/2
Now that you know how to
multiply fractions, let’s try some
together.
1/3
x 2/3
2/9 3/10
2/3
x 2/3
4/9
1/2
x 2/2
2/4
3/4
x 1/2
3/8
1/2
x 1/3
1/6
1/2
x 1/4
1/8
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