Add 42/70 and 7/21
42/70 + 7/21 is 14/15.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 21 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 70 × 3 = 210,
42/70 = 42 × 3/70 × 3 = 126/210 - Likewise, for the 2nd fraction, since 21 × 10 = 210,
7/21 = 7 × 10/21 × 10 = 70/210 - Add the two like fractions:
126/210 + 70/210 = 126 + 70/210 = 196/210 - 196/210 simplified gives 14/15
- So, 42/70 + 7/21 = 14/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/70+7/21 42/70+14/21 42/70+7/42 42/70+7/63 42/70+35/21 42/70+49/21