The least common denominator is the smallest positive denominator that can represent every fraction in a set. It is the least common multiple of the denominators as written. The main LCD calculator provides the fastest general solution.
Start with the denominators
For 3/4 and 5/6, use 4 and 6. The numerators do not participate in the LCD calculation.
Use the LCM
Prime factorization gives 4 = 2² and 6 = 2 × 3. Taking the highest power of each prime gives 2² × 3 = 12, so the LCD is 12. Explore this in the prime-factorization calculator or compare it with the multiples method.
Rewrite equivalent fractions
Multiply 3/4 by 3/3 to get 9/12. Multiply 5/6 by 2/2 to get 10/12. Try other values in the step-by-step LCD solver.