Add 21/42 and 15/72
21/42 + 15/72 is 17/24.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 72 is 504
Next, find the equivalent fraction of both fractional numbers with denominator 504 - For the 1st fraction, since 42 × 12 = 504,
21/42 = 21 × 12/42 × 12 = 252/504 - Likewise, for the 2nd fraction, since 72 × 7 = 504,
15/72 = 15 × 7/72 × 7 = 105/504 - Add the two like fractions:
252/504 + 105/504 = 252 + 105/504 = 357/504 - 357/504 simplified gives 17/24
- So, 21/42 + 15/72 = 17/24
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 21/42+30/72 21/84+15/72 63/42+15/72 21/42+45/72 21/42+75/72