Subtract 18/21 from 1/90
1/90 - 18/21 is -533/630.
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,
18/21 = 18 × 30/21 × 30 = 540/630 - Subtract the two like fractions:
7/630 - 540/630 = 7 - 540/630 = -533/630
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 2/90-18/21 1/90-36/21 1/90-18/42 3/90-18/21 1/90-54/21 1/90-18/63 5/90-18/21 1/90-90/21 7/90-18/21