multiplying fractions by: greg stark ec&i 831 multiplying fractions numerator...
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Multiplying Fractions
By: Greg StarkEC&I 831
Multiplying Fractions
Numerator--------------------Denominator Represents the number of parts into
which the whole has been divided
Represents the number of partsof a whole we have.
To multiply fractions together, we perform 3 steps:
1. Multiply the factors numerators together to form the numerator of the product
2. Multiply the factors denominators together to form the denominator of the product
3. Reduce the product into lowest terms
Multiplying Fractions
14
1
3x
For example:
= =1 x 1
4 x 3
112
Translation: what is 1/3 of 1/4
Multiplying Fractions
23
3
15x
Another example:
= =2 x 3
3 x 156
45
Translation: what is 3/15 of 2/3
645
÷ 3----
÷ 3=
215
Multiplying Fractions
37
14
15x
One more example:
= =3 x 14
7 x 15
42105
Translation: what is 14/15 of 3/7
42105
÷ 21----
÷ 21=
25
“Cancelling”It is possible to reduce fractions before you multiply by dividing out the common factors in the numerators and the denominators of the factors
37
1415
x = =1 x 21 x 5
25
Remember: the common factors must exist in both the numerator and the denominator to be reduced out
÷ 3
÷ 3
÷ 7
÷ 7
1
5
2
\1
\\\
“Cancelling”Another example
910
1524
x = =3 x 32 x 8
916
Remember: the common factors must exist in both the numerator and the denominator to be reduced out
÷ 3
÷ 3
÷ 5
÷ 5
3
8
3
\2
\\\
Review: multiplying fractions
1. Multiply the factors numerators together to form the numerator of the product
2. Multiply the factors denominators together to form the denominator of the product
3. Reduce the product into lowest terms. You may reduce factors before multiplying if the factor exists in both the numerator and the denominator
To multiply fractions together, we perform 3 steps: