Adding Fractions with Unlike Denominators
1/4 + 2/3 =
11/12
4/5 - 1/3 =
7/15
2/8
1/4
What is the TOP number of a fraction called?
The Numerator
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
20/30
2/3
What is the BOTTOM number of the denominator called?
The Denominator
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
18/36
1/2
A fraction with a numerator that is LARGER than the denominator
An improper fraction
List the factors of 21
1, 3, 7, 21
1/2 + 1/3 =
5/6
6/7 - 1/2 =
5/14
12/36
1/3
If the denominators are the same for two fractions, do we have to find the least common denominator (LCD)?
No, we can add or subtract the fractions as is.
List the factors of 9
1, 3, 9
1/4 + 3/7 =
19/28
9/10 - 1/4 =
13/20
21/28
3/4
What is the first thing you do when you are adding or subtracting fractions with unlike denominators?
Find the multiples of the two denominators.
List the factors of 8
1, 2, 4, 8