Add 4/21 and 63/18, Solve 4/21 + 3 9/18 as a fraction

Add 4/21 and 63/18

1^st number: 4/21, 2^nd number: 3 9/18

4/21 + 63/18 is 155/42.

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

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 21 × 6 = 126,
4/21 = 4 × 6/21 × 6 = 24/126
Likewise, for the 2nd fraction, since 18 × 7 = 126,
63/18 = 63 × 7/18 × 7 = 441/126
Add the two like fractions:
24/126 + 441/126 = 24 + 441/126 = 465/126
465/126 simplified gives 155/42
So, 4/21 + 63/18 = 155/42
In mixed form: 329/42

MathStep (Works offline)

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