Add 21/15 and 54/21
1st number: 1 6/15, 2nd number: 2 12/21
21/15 + 54/21 is 139/35.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 15 and 21 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 15 × 7 = 105,
21/15 = 21 × 7/15 × 7 = 147/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
54/21 = 54 × 5/21 × 5 = 270/105 - Add the two like fractions:
147/105 + 270/105 = 147 + 270/105 = 417/105 - 417/105 simplified gives 139/35
- So, 21/15 + 54/21 = 139/35
In mixed form: 334/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/15+54/21 21/30+54/21 21/15+54/42 63/15+54/21 21/45+54/21 21/15+54/63 21/75+54/21