Subtract 7/90 from 1/21
1/21 - 7/90 is -19/630.
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,
7/90 = 7 × 7/90 × 7 = 49/630 - Subtract the two like fractions:
30/630 - 49/630 = 30 - 49/630 = -19/630
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 2/21-7/90 1/21-14/90 1/42-7/90 3/21-7/90 1/21-21/90 1/63-7/90 5/21-7/90 1/21-35/90 7/21-7/90 1/21-49/90