Adding Fractions with Unlike Denominators
1/4 + 2/3 =
11/12
4/5 - 1/3 =
7/15
1/2 and 3/5
LCD: 10
If the denominators are the same for two fractions, do we have to find the common denominator?
No, we can add or subtract the fractions as is.
List the factors of 18
1, 2, 3, 6, 9, 18
4/9 + 1/6 =
*write your answer in simplest form
11/18
4/3 - 2/7 =
22/21
5/12 and 2/9
LCD: 36
What does the denominator mean?
Equal parts the whole is divided into
List the factors of 30
1, 2, 3, 5, 6, 10, 15, 30
3/4 + 1/9 =
31/36
3/4 - 1/9 =
23/36
1/7 and 4/8
LCD: 56
What is the first step when adding and subtracting fractions with unlike denominators?
Rename the fractions.
List the factors of 21
1, 3, 7, 21
1/2 + 1/3 =
5/6
6/7 - 1/2 =
5/14
9/10 and 5/6
LCD: 30
What does the numerator mean in any fraction?
Parts of the whole that are counted
List the factors of 9
1, 3, 9
1/4 + 3/7 =
19/28
9/10 - 1/4 =
*Write your answer in simplest form
13/20
1/4 and 2/3
LCD: 12
5/6 x 24
What is 20
List the factors of 8
1, 2, 4, 8