Add 2/5 and 7/21
2/5 + 7/21 is 11/15.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 5 and 21 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 5 × 21 = 105,
2/5 = 2 × 21/5 × 21 = 42/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
7/21 = 7 × 5/21 × 5 = 35/105 - Add the two like fractions:
42/105 + 35/105 = 42 + 35/105 = 77/105 - 77/105 simplified gives 11/15
- So, 2/5 + 7/21 = 11/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 4/5+7/21 2/5+14/21 2/10+7/21 2/5+7/42 6/5+7/21 2/15+7/21 2/5+7/63 10/5+7/21 2/5+35/21 2/25+7/21 14/5+7/21 2/5+49/21 2/35+7/21