Add 20/21 and 21/72
20/21 + 21/72 is 209/168.
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,
20/21 = 20 × 24/21 × 24 = 480/504 - Likewise, for the 2nd fraction, since 72 × 7 = 504,
21/72 = 21 × 7/72 × 7 = 147/504 - Add the two like fractions:
480/504 + 147/504 = 480 + 147/504 = 627/504 - 627/504 simplified gives 209/168
- So, 20/21 + 21/72 = 209/168
In mixed form: 141/168
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/21+21/72 20/21+42/72 20/42+21/72 60/21+21/72 20/21+63/72 20/63+21/72