Add 21/90 and 90/27, Solve 21/90 + 3 9/27 as a fraction

Add 21/90 and 90/27

1^st number: 21/90, 2^nd number: 3 9/27

21/90 + 90/27 is 107/30.

Find the least common denominator or LCM of the two denominators:
LCM of 90 and 27 is 270

Next, find the equivalent fraction of both fractional numbers with denominator 270
For the 1st fraction, since 90 × 3 = 270,
21/90 = 21 × 3/90 × 3 = 63/270
Likewise, for the 2nd fraction, since 27 × 10 = 270,
90/27 = 90 × 10/27 × 10 = 900/270
Add the two like fractions:
63/270 + 900/270 = 63 + 900/270 = 963/270
963/270 simplified gives 107/30
So, 21/90 + 90/27 = 107/30
In mixed form: 317/30

MathStep (Works offline)

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