Student Resources—746

Math Skill Handbook
Math Skill Handbook
Multiply Fractions To multiply with fractions,
multiply the numerators and multiply
the denominators. Find the simplest form if
necessary.
Example Multiply 3
by 1
5 3 .
Step 1 Multiply the numerators and denominators.
3
3 1)
3
1 ( 5 3 ( 5 3)
15
Step 2 Find the GCF.
3
(GCF, 3)
15
Step 3 Divide the numerator and denominator by
the GCF.
3 5
1, 1 5
3 3
1
5
3
multiplied by 1 is 1
5 3 5 .
3 5
Practice Problem Multiply by . 14
16
Find a Reciprocal Two numbers whose
product is 1 are called multiplicative
inverses, or reciprocals.
Example Find the reciprocal of 3
8 .
Step 1 Inverse the fraction by putting the denominator
on top and the numerator on the
bottom.
8
3
The reciprocal of 3
is 8
8 3 .
Practice Problem Find the reciprocal of 4
9 .
778 STUDENT RESOURCES
Divide Fractions To divide one fraction
by another fraction, multiply the dividend
by the reciprocal of the divisor. Find the
simplest form if necessary.
Example 1 Divide 1
by 1
9 3 .
Step 1 Find the reciprocal of the divisor.
The reciprocal of 1
is 3
3 1 .
Step 2 Multiply the dividend by the reciprocal of the
divisor.
1
9
1
3
1
1
3 (
9 1 ( 9
3)
1)
3
9
Step 3 Find the GCF.
3
(GCF, 3)
9
Step 4 Divide the numerator and denominator by
the GCF.
3
1, 9 3
3 3
1
3
1
divided by 1 is 1
9 3 3 .
Example 2 Divide 3
by 1
5 4 .
Step 1 Find the reciprocal of the divisor.
The reciprocal of 1
is 4
4 1 .
Step 2 Multiply the dividend by the reciprocal of the
divisor.
3
5
1
4
3
3
4 (
5 1 ( 5
3
2
divided by 1 is 1 or 2
5 4 5
2
5 .
4)
1)
12
5
3 7
Practice Problem Divide by . 11
10