Subtract 21/81 from 1/2
1/2 - 21/81 is 13/54.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 2 and 81 is 162
Next, find the equivalent fraction of both fractional numbers with denominator 162 - For the 1st fraction, since 2 × 81 = 162,
1/2 = 1 × 81/2 × 81 = 81/162 - Likewise, for the 2nd fraction, since 81 × 2 = 162,
21/81 = 21 × 2/81 × 2 = 42/162 - Subtract the two like fractions:
81/162 - 42/162 = 81 - 42/162 = 39/162 - After reducing the fraction, the answer is 13/54
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 1/2-42/81 1/4-21/81 3/2-21/81 1/2-63/81 1/6-21/81 5/2-21/81 1/10-21/81 7/2-21/81 1/14-21/81