Subtract 4/21 from 1/90
1/90 - 4/21 is -113/630.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
1/90 = 1 × 7/90 × 7 = 7/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
4/21 = 4 × 30/21 × 30 = 120/630 - Subtract the two like fractions:
7/630 - 120/630 = 7 - 120/630 = -113/630
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 2/90-4/21 1/90-8/21 1/90-4/42 3/90-4/21 1/90-12/21 1/90-4/63 5/90-4/21 1/90-20/21 7/90-4/21 1/90-28/21