Subtract 81/90 from 1/21
1/21 - 81/90 is -179/210.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 21 × 30 = 630,
1/21 = 1 × 30/21 × 30 = 30/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
81/90 = 81 × 7/90 × 7 = 567/630 - Subtract the two like fractions:
30/630 - 567/630 = 30 - 567/630 = -537/630 - After reducing the fraction, the answer is -179/210
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 2/21-81/90 1/42-81/90 3/21-81/90 1/63-81/90 5/21-81/90 7/21-81/90