Add 3/9 and 40/21, Solve 3/9 + 1 19/21 as a fraction

Add 3/9 and 40/21

1^st number: 3/9, 2^nd number: 1 19/21

3/9 + 40/21 is 47/21.

Find the least common denominator or LCM of the two denominators:
LCM of 9 and 21 is 63

Next, find the equivalent fraction of both fractional numbers with denominator 63
For the 1st fraction, since 9 × 7 = 63,
3/9 = 3 × 7/9 × 7 = 21/63
Likewise, for the 2nd fraction, since 21 × 3 = 63,
40/21 = 40 × 3/21 × 3 = 120/63
Add the two like fractions:
21/63 + 120/63 = 21 + 120/63 = 141/63
141/63 simplified gives 47/21
So, 3/9 + 40/21 = 47/21
In mixed form: 25/21

MathStep (Works offline)

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