Add 27/30 and 5/21, Solve 27/30 + 5/21 as a fraction

Add 27/30 and 5/21

27/30 + 5/21 is 239/210.

Find the least common denominator or LCM of the two denominators:
LCM of 30 and 21 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 30 × 7 = 210,
27/30 = 27 × 7/30 × 7 = 189/210
Likewise, for the 2nd fraction, since 21 × 10 = 210,
5/21 = 5 × 10/21 × 10 = 50/210
Add the two like fractions:
189/210 + 50/210 = 189 + 50/210 = 239/210
So, 27/30 + 5/21 = 239/210
In mixed form: 129/210

MathStep (Works offline)

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