Subtract 1/20 from 20/21
20/21 - 1/20 is 379/420.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 21 × 20 = 420,
20/21 = 20 × 20/21 × 20 = 400/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
1/20 = 1 × 21/20 × 21 = 21/420 - Subtract the two like fractions:
400/420 - 21/420 = 400 - 21/420 = 379/420
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/21-1/20 20/21-2/20 20/42-1/20 20/21-1/40 60/21-1/20 20/21-3/20 20/63-1/20 20/21-1/60 20/21-5/20 20/21-7/20