Subtract 1/7 from 8/21
8/21 - 1/7 is 5/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 7 is 21
Next, find the equivalent fraction of both fractional numbers with denominator 21 - For the 1st fraction, since 21 × 1 = 21,
8/21 = 8 × 1/21 × 1 = 8/21 - Likewise, for the 2nd fraction, since 7 × 3 = 21,
1/7 = 1 × 3/7 × 3 = 3/21 - Subtract the two like fractions:
8/21 - 3/21 = 8 - 3/21 = 5/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/21-1/7 8/21-2/7 8/42-1/7 8/21-1/14 24/21-1/7 8/21-3/7 8/63-1/7 8/21-1/21 40/21-1/7 8/21-5/7 8/21-1/35 56/21-1/7 8/21-1/49