Answers

Subtract 5/81 from 21/30

21/30 - 5/81 is 517/810.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 30 and 81 is 810
   
   Next, find the equivalent fraction of both fractional numbers with denominator 810
2. For the 1st fraction, since 30 × 27 = 810,
   21/30 = 21 × 27/30 × 27 = 567/810
3. Likewise, for the 2nd fraction, since 81 × 10 = 810,
   5/81 = 5 × 10/81 × 10 = 50/810
4. Subtract the two like fractions:
   567/810 - 50/810 = 567 - 50/810 = 517/810

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad

Related: ⁴²/₃₀-⁵/₈₁ ²¹/₃₀-¹⁰/₈₁ ²¹/₆₀-⁵/₈₁ ⁶³/₃₀-⁵/₈₁ ²¹/₃₀-¹⁵/₈₁ ²¹/₉₀-⁵/₈₁ ²¹/₃₀-²⁵/₈₁ ²¹/₃₀-³⁵/₈₁

Subtract Fractions Calculator