Subtract 42/81 from 8/21
8/21 - 42/81 is -26/189.
Steps for subtracting 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,
8/21 = 8 × 27/21 × 27 = 216/567 - Likewise, for the 2nd fraction, since 81 × 7 = 567,
42/81 = 42 × 7/81 × 7 = 294/567 - Subtract the two like fractions:
216/567 - 294/567 = 216 - 294/567 = -78/567 - After reducing the fraction, the answer is -26/189
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/21-42/81 8/21-84/81 8/42-42/81 24/21-42/81 8/63-42/81 40/21-42/81 56/21-42/81