Add 7/21 and 81/4, Solve 7/21 + 20 1/4 as a fraction

Add 7/21 and 81/4

1^st number: 7/21, 2^nd number: 20 1/4

7/21 + 81/4 is 247/12.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 4 is 84

Next, find the equivalent fraction of both fractional numbers with denominator 84
For the 1st fraction, since 21 × 4 = 84,
7/21 = 7 × 4/21 × 4 = 28/84
Likewise, for the 2nd fraction, since 4 × 21 = 84,
81/4 = 81 × 21/4 × 21 = 1701/84
Add the two like fractions:
28/84 + 1701/84 = 28 + 1701/84 = 1729/84
1729/84 simplified gives 247/12
So, 7/21 + 81/4 = 247/12
In mixed form: 207/12

MathStep (Works offline)

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