Add 7/12 and 70/21, Solve 7/12 + 3 7/21 as a fraction

Add 7/12 and 70/21

1^st number: 7/12, 2^nd number: 3 7/21

7/12 + 70/21 is 47/12.

Find the least common denominator or LCM of the two denominators:
LCM of 12 and 21 is 84

Next, find the equivalent fraction of both fractional numbers with denominator 84
For the 1st fraction, since 12 × 7 = 84,
7/12 = 7 × 7/12 × 7 = 49/84
Likewise, for the 2nd fraction, since 21 × 4 = 84,
70/21 = 70 × 4/21 × 4 = 280/84
Add the two like fractions:
49/84 + 280/84 = 49 + 280/84 = 329/84
329/84 simplified gives 47/12
So, 7/12 + 70/21 = 47/12
In mixed form: 311/12

MathStep (Works offline)

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