Add 21/84 and 18/15
1st number: 21/84, 2nd number: 1 3/15
21/84 + 18/15 is 29/20.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 84 and 15 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 84 × 5 = 420,
21/84 = 21 × 5/84 × 5 = 105/420 - Likewise, for the 2nd fraction, since 15 × 28 = 420,
18/15 = 18 × 28/15 × 28 = 504/420 - Add the two like fractions:
105/420 + 504/420 = 105 + 504/420 = 609/420 - 609/420 simplified gives 29/20
- So, 21/84 + 18/15 = 29/20
In mixed form: 19/20
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/84+18/15 21/84+36/15 21/84+18/30 63/84+18/15 21/84+54/15 21/84+18/45 21/84+90/15 21/84+18/75