Subtract 5/81 from 21/45
21/45 - 5/81 is 164/405.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 81 is 405
Next, find the equivalent fraction of both fractional numbers with denominator 405 - For the 1st fraction, since 45 × 9 = 405,
21/45 = 21 × 9/45 × 9 = 189/405 - Likewise, for the 2nd fraction, since 81 × 5 = 405,
5/81 = 5 × 5/81 × 5 = 25/405 - Subtract the two like fractions:
189/405 - 25/405 = 189 - 25/405 = 164/405
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/45-5/81 21/45-10/81 21/90-5/81 63/45-5/81 21/45-15/81 21/45-25/81 21/45-35/81