Add 21/12 and 18/9
1st number: 1 9/12, 2nd number: 2 0/9
21/12 + 18/9 is 15/4.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 12 and 9 is 36
Next, find the equivalent fraction of both fractional numbers with denominator 36 - For the 1st fraction, since 12 × 3 = 36,
21/12 = 21 × 3/12 × 3 = 63/36 - Likewise, for the 2nd fraction, since 9 × 4 = 36,
18/9 = 18 × 4/9 × 4 = 72/36 - Add the two like fractions:
63/36 + 72/36 = 63 + 72/36 = 135/36 - 135/36 simplified gives 15/4
- So, 21/12 + 18/9 = 15/4
In mixed form: 33/4
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/12+18/9 21/12+36/9 21/24+18/9 63/12+18/9 21/12+54/9 21/36+18/9 21/12+18/27 21/12+90/9 21/60+18/9 21/12+18/45 21/84+18/9 21/12+18/63