Subtract 81/8 from 8/21
1st number: 8/21, 2nd number: 10 1/8
8/21 - 81/8 is -1637/168.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 8 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 21 × 8 = 168,
8/21 = 8 × 8/21 × 8 = 64/168 - Likewise, for the 2nd fraction, since 8 × 21 = 168,
81/8 = 81 × 21/8 × 21 = 1701/168 - Subtract the two like fractions:
64/168 - 1701/168 = 64 - 1701/168 = -1637/168
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/21-81/8 8/42-81/8 8/21-81/16 24/21-81/8 8/63-81/8 8/21-81/24 40/21-81/8 8/21-81/40 56/21-81/8 8/21-81/56