Add 21/30 and 10/8, Solve 21/30 + 1 2/8 as a fraction

Add 21/30 and 10/8

1^st number: 21/30, 2^nd number: 1 2/8

21/30 + 10/8 is 39/20.

Find the least common denominator or LCM of the two denominators:
LCM of 30 and 8 is 120

Next, find the equivalent fraction of both fractional numbers with denominator 120
For the 1st fraction, since 30 × 4 = 120,
21/30 = 21 × 4/30 × 4 = 84/120
Likewise, for the 2nd fraction, since 8 × 15 = 120,
10/8 = 10 × 15/8 × 15 = 150/120
Add the two like fractions:
84/120 + 150/120 = 84 + 150/120 = 234/120
234/120 simplified gives 39/20
So, 21/30 + 10/8 = 39/20
In mixed form: 119/20

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad