Add 21/5 and 15/21
1st number: 4 1/5, 2nd number: 15/21
21/5 + 15/21 is 172/35.
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,
21/5 = 21 × 21/5 × 21 = 441/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
15/21 = 15 × 5/21 × 5 = 75/105 - Add the two like fractions:
441/105 + 75/105 = 441 + 75/105 = 516/105 - 516/105 simplified gives 172/35
- So, 21/5 + 15/21 = 172/35
In mixed form: 432/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/5+15/21 21/5+30/21 21/10+15/21 21/5+15/42 63/5+15/21 21/5+45/21 21/15+15/21 21/5+15/63 21/5+75/21 21/25+15/21 21/35+15/21