Subtract 20/81 from 21/2
1st number: 10 1/2, 2nd number: 20/81
21/2 - 20/81 is 1661/162.
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,
21/2 = 21 × 81/2 × 81 = 1701/162 - Likewise, for the 2nd fraction, since 81 × 2 = 162,
20/81 = 20 × 2/81 × 2 = 40/162 - Subtract the two like fractions:
1701/162 - 40/162 = 1701 - 40/162 = 1661/162 - In mixed form: 1041/162
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/2-20/81 21/2-40/81 21/4-20/81 63/2-20/81 21/2-60/81 21/6-20/81 21/10-20/81 21/14-20/81