Add 21/42 and 28/70
21/42 + 28/70 is 9/10.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 70 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 42 × 5 = 210,
21/42 = 21 × 5/42 × 5 = 105/210 - Likewise, for the 2nd fraction, since 70 × 3 = 210,
28/70 = 28 × 3/70 × 3 = 84/210 - Add the two like fractions:
105/210 + 84/210 = 105 + 84/210 = 189/210 - 189/210 simplified gives 9/10
- So, 21/42 + 28/70 = 9/10
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 21/42+56/70 21/84+28/70 63/42+28/70 21/42+84/70