Add 81/21 and 81/72
1st number: 3 18/21, 2nd number: 1 9/72
81/21 + 81/72 is 279/56.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 72 is 504
Next, find the equivalent fraction of both fractional numbers with denominator 504 - For the 1st fraction, since 21 × 24 = 504,
81/21 = 81 × 24/21 × 24 = 1944/504 - Likewise, for the 2nd fraction, since 72 × 7 = 504,
81/72 = 81 × 7/72 × 7 = 567/504 - Add the two like fractions:
1944/504 + 567/504 = 1944 + 567/504 = 2511/504 - 2511/504 simplified gives 279/56
- So, 81/21 + 81/72 = 279/56
In mixed form: 455/56
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 81/42+81/72 81/63+81/72