Add 12/21 and 42/81
12/21 + 42/81 is 206/189.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 81 is 567
Next, find the equivalent fraction of both fractional numbers with denominator 567 - For the 1st fraction, since 21 × 27 = 567,
12/21 = 12 × 27/21 × 27 = 324/567 - Likewise, for the 2nd fraction, since 81 × 7 = 567,
42/81 = 42 × 7/81 × 7 = 294/567 - Add the two like fractions:
324/567 + 294/567 = 324 + 294/567 = 618/567 - 618/567 simplified gives 206/189
- So, 12/21 + 42/81 = 206/189
In mixed form: 117/189
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/21+42/81 12/21+84/81 12/42+42/81 36/21+42/81 12/63+42/81 60/21+42/81 84/21+42/81