FRACTIONS
Review of Introductory Mathematics
Example 1:
Add
and
1
15
7
10
Solution:
Step 1:
Find primes of each denominator.
15 = 5 x 3
10 = 5 x 2
Step 2:
In the example, 15 is the largest denominator, so use the 5 and the 3; now
look at the second denominator’s primes—the five already appears in the
list, but the 2 does not, so use the 2.
5 x 3 x 2 = 30
Step 3:
Rewrite with least common denominators.
1
15
2
30
7
10
21
30
Step 4:
Add the new fractions.
2
30
21
30
23
30
Example 2:
Add
1
7
2
3
11
12
4
6
Solution:
Step 1:
Find primes of each denominator.
7 = 7 (already is a prime number)
3 = 3 (already is a prime number)
12 = 2 x 6 = 2 x 2 x 3
6 = 2 x 3
Step 2:
12 is the largest, so start with
2 x 2 x 3
MA-01
Page 32
Rev. 0
