Subtract 3/81 from 7/21
7/21 - 3/81 is 8/27.
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,
7/21 = 7 × 27/21 × 27 = 189/567 - Likewise, for the 2nd fraction, since 81 × 7 = 567,
3/81 = 3 × 7/81 × 7 = 21/567 - Subtract the two like fractions:
189/567 - 21/567 = 189 - 21/567 = 168/567 - After reducing the fraction, the answer is 8/27
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/21-3/81 7/21-6/81 7/42-3/81 7/21-9/81 7/63-3/81 35/21-3/81 7/21-15/81 49/21-3/81 7/21-21/81