Add 64/21 and 7/20, Solve 3 1/21 + 7/20 as a fraction

Add 64/21 and 7/20

1^st number: 3 1/21, 2^nd number: 7/20

64/21 + 7/20 is 1427/420.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 21 × 20 = 420,
64/21 = 64 × 20/21 × 20 = 1280/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
7/20 = 7 × 21/20 × 21 = 147/420
Add the two like fractions:
1280/420 + 147/420 = 1280 + 147/420 = 1427/420
So, 64/21 + 7/20 = 1427/420
In mixed form: 3167/420

MathStep (Works offline)

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