Add 9/18 and 70/21, Solve 9/18 + 3 7/21 as a fraction

Add 9/18 and 70/21

1^st number: 9/18, 2^nd number: 3 7/21

9/18 + 70/21 is 23/6.

Find the least common denominator or LCM of the two denominators:
LCM of 18 and 21 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 18 × 7 = 126,
9/18 = 9 × 7/18 × 7 = 63/126
Likewise, for the 2nd fraction, since 21 × 6 = 126,
70/21 = 70 × 6/21 × 6 = 420/126
Add the two like fractions:
63/126 + 420/126 = 63 + 420/126 = 483/126
483/126 simplified gives 23/6
So, 9/18 + 70/21 = 23/6
In mixed form: 35/6

MathStep (Works offline)

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