Add 21/72 and 15/7, Solve 21/72 + 2 1/7 as a fraction

Add 21/72 and 15/7

1^st number: 21/72, 2^nd number: 2 1/7

21/72 + 15/7 is 409/168.

Find the least common denominator or LCM of the two denominators:
LCM of 72 and 7 is 504

Next, find the equivalent fraction of both fractional numbers with denominator 504
For the 1st fraction, since 72 × 7 = 504,
21/72 = 21 × 7/72 × 7 = 147/504
Likewise, for the 2nd fraction, since 7 × 72 = 504,
15/7 = 15 × 72/7 × 72 = 1080/504
Add the two like fractions:
147/504 + 1080/504 = 147 + 1080/504 = 1227/504
1227/504 simplified gives 409/168
So, 21/72 + 15/7 = 409/168
In mixed form: 273/168

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad