Add Fractions with Unlike Denominators

Use least common denominator to find the sum of fractions with unlike denominators.

For example: Let's find the sum of:

2
7
and
1
4

Notice that 28 is the common denominator.

First of all, rewrite both the fractions having common denominator 28.

Multiply the numerator and denominator of
2
7
 by 4 to find an equivalent fraction.
2
7
×
4
4
=
8
28
Multiply the numerator and denominator of
1
4
 by 7 to find an equivalent fraction.
1
4
×
7
7
=
7
28

Now add fractions. Add numerators and keep denominators the same.

2
7
+
1
4
=
8
28
+
7
28
=
15
28
is written in simplest form.

 

So, the required sum is
15
28
.