1) A fraction represents a part of a whole. Adding fractions is different than adding whole numbers. There are two types of fraction addition problems: those where the fractions have the same denominator, and those where the fractions have different denominators. 2) For problems where the fractions have the same denominator, you simply add the numerators and keep the same denominator. 3) For problems where the fractions have different denominators, you find the least common multiple of the denominators and convert the fractions to equivalent fractions with that denominator before adding the numerators and keeping the common denominator.

1. ADDITION
OF
FRACTIONS

2. • A fraction is part of an
entire object.

3. • Adding fractions is done
differently than the usual
numbers. Normally, while
adding or subtracting
fractions you will find two
types of problems.

4. Type 1:
Where the fractions being
added have the same
denominator.

5. 9
4
9
2
9
2
8
7
8
3
8
4
11
8
11
5
11
3
=+
=+
=+
Examples:
1.
2.
3.

6. • As you know, fractions
represent parts of the
whole. So, when these
parts are from the whole
broken into same number
of parts it is easy to add
them.

7. • For Type 1 problems, we
just need to add the top
parts (numerator) of the
fractions and leave the
denominator as such.

8. Type 2
Where the fractions being
added have different
denominators

9. 12
11
2
1
12
5
15
11
5
2
3
1
=+
=+
EXAMPLES:
1.
2.

10. 5
2
3
1
+
• To solve for:
• First we will need to look
at the denominators 3 and
5 and see what multiples of
these numbers are
common.

11. Multiples of 3 are:
3 6 9 12 15 18 21
Multiples of 5 are:
5 10 15 20 25

12. • so, in multiples of 3 and 5 the
least common multiple is 15.
• now, we will change 1/3 and 2/5
into their equivalent fractions
with denominator 15

13. 





==






====
35
32
15
6
10
4
5
2
53
51
15
5
12
4
9
3
6
2
3
1
x
x
x
x

14. 15
11
15
6
15
5
35
32
53
51
=
+=
+=
x
x
x
x

15. 12
1
12
5
+
• To solve for:
• Again, we need to look at the
denominators first and see
what multiples of them are
common

16. • Multiples of 12:
12 24 36
• Multiples of 2:
2 4 6 8 10 12 14
• So, we find that 12 is the least
common multiple.

17. 12
11
12
6
12
5
62
61
112
15
=
+=
+=
x
x
x
x

18. 9
5
6
1
5
1
5
3
6
2
3
1
+
+
+
Solve for the following:
1.
2.
3.

19. 12
2
2
6
3
3
3
1
3
3
2
5
+
+
Assignment:
• Solve for the following:
1.
2.