Add 21/15 and 72/21
1st number: 1 6/15, 2nd number: 3 9/21
21/15 + 72/21 is 169/35.
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,
72/21 = 72 × 5/21 × 5 = 360/105 - Add the two like fractions:
147/105 + 360/105 = 147 + 360/105 = 507/105 - 507/105 simplified gives 169/35
- So, 21/15 + 72/21 = 169/35
In mixed form: 429/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/15+72/21 21/30+72/21 21/15+72/42 63/15+72/21 21/45+72/21 21/15+72/63 21/75+72/21