Add 12/10 and 21/42, Solve 1 2/10 + 21/42 as a fraction

Add 12/10 and 21/42

1^st number: 1 2/10, 2^nd number: 21/42

12/10 + 21/42 is 17/10.

Find the least common denominator or LCM of the two denominators:
LCM of 10 and 42 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 10 × 21 = 210,
12/10 = 12 × 21/10 × 21 = 252/210
Likewise, for the 2nd fraction, since 42 × 5 = 210,
21/42 = 21 × 5/42 × 5 = 105/210
Add the two like fractions:
252/210 + 105/210 = 252 + 105/210 = 357/210
357/210 simplified gives 17/10
So, 12/10 + 21/42 = 17/10
In mixed form: 17/10

MathStep (Works offline)

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