Add 21/84 and 28/18, Solve 21/84 + 1 10/18 as a fraction

Add 21/84 and 28/18

1^st number: 21/84, 2^nd number: 1 10/18

21/84 + 28/18 is 65/36.

Find the least common denominator or LCM of the two denominators:
LCM of 84 and 18 is 252

Next, find the equivalent fraction of both fractional numbers with denominator 252
For the 1st fraction, since 84 × 3 = 252,
21/84 = 21 × 3/84 × 3 = 63/252
Likewise, for the 2nd fraction, since 18 × 14 = 252,
28/18 = 28 × 14/18 × 14 = 392/252
Add the two like fractions:
63/252 + 392/252 = 63 + 392/252 = 455/252
455/252 simplified gives 65/36
So, 21/84 + 28/18 = 65/36
In mixed form: 129/36

MathStep (Works offline)

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