Add 21/12 and 25/21
1st number: 1 9/12, 2nd number: 1 4/21
21/12 + 25/21 is 247/84.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 12 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 12 × 7 = 84,
21/12 = 21 × 7/12 × 7 = 147/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
25/21 = 25 × 4/21 × 4 = 100/84 - Add the two like fractions:
147/84 + 100/84 = 147 + 100/84 = 247/84 - So, 21/12 + 25/21 = 247/84
In mixed form: 279/84
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/12+25/21 21/12+50/21 21/24+25/21 21/12+25/42 63/12+25/21 21/12+75/21 21/36+25/21 21/12+25/63 21/60+25/21 21/84+25/21