Add 3/5 and 7/21
3/5 + 7/21 is 14/15.
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,
3/5 = 3 × 21/5 × 21 = 63/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
7/21 = 7 × 5/21 × 5 = 35/105 - Add the two like fractions:
63/105 + 35/105 = 63 + 35/105 = 98/105 - 98/105 simplified gives 14/15
- So, 3/5 + 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: 6/5+7/21 3/5+14/21 3/10+7/21 3/5+7/42 9/5+7/21 3/15+7/21 3/5+7/63 15/5+7/21 3/5+35/21 3/25+7/21 21/5+7/21 3/5+49/21 3/35+7/21