Add 7/4 and 42/21, Solve 1 3/4 + 2 0/21 as a fraction

Add 7/4 and 42/21

1^st number: 1 3/4, 2^nd number: 2 0/21

7/4 + 42/21 is 15/4.

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

Next, find the equivalent fraction of both fractional numbers with denominator 84
For the 1st fraction, since 4 × 21 = 84,
7/4 = 7 × 21/4 × 21 = 147/84
Likewise, for the 2nd fraction, since 21 × 4 = 84,
42/21 = 42 × 4/21 × 4 = 168/84
Add the two like fractions:
147/84 + 168/84 = 147 + 168/84 = 315/84
315/84 simplified gives 15/4
So, 7/4 + 42/21 = 15/4
In mixed form: 33/4

MathStep (Works offline)

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