Subtract 5/81 from 7/90
7/90 - 5/81 is 13/810.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 81 is 810
Next, find the equivalent fraction of both fractional numbers with denominator 810 - For the 1st fraction, since 90 × 9 = 810,
7/90 = 7 × 9/90 × 9 = 63/810 - Likewise, for the 2nd fraction, since 81 × 10 = 810,
5/81 = 5 × 10/81 × 10 = 50/810 - Subtract the two like fractions:
63/810 - 50/810 = 63 - 50/810 = 13/810
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/90-5/81 7/90-10/81 21/90-5/81 7/90-15/81 35/90-5/81 7/90-25/81 49/90-5/81 7/90-35/81