Add 21/84 and 12/9
1st number: 21/84, 2nd number: 1 3/9
21/84 + 12/9 is 19/12.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 84 and 9 is 252
Next, find the equivalent fraction of both fractional numbers with denominator 252 - For the 1st fraction, since 84 × 3 = 252,
21/84 = 21 × 3/84 × 3 = 63/252 - Likewise, for the 2nd fraction, since 9 × 28 = 252,
12/9 = 12 × 28/9 × 28 = 336/252 - Add the two like fractions:
63/252 + 336/252 = 63 + 336/252 = 399/252 - 399/252 simplified gives 19/12
- So, 21/84 + 12/9 = 19/12
In mixed form: 17/12
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/84+12/9 21/84+24/9 21/84+12/18 63/84+12/9 21/84+36/9 21/84+12/27 21/84+60/9 21/84+12/45 21/84+84/9 21/84+12/63