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Common Denominator Calculator

Online common denominator calculator. Enter two fractions to find the least common denominator and rewrite them over it, with full steps—great for fractions.

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a/b and c/d → least common multiple of denominators
1/63/8→4/249/24
Numerator 1
Denominator 1
Numerator 2
Denominator 2

📖 Tutorial | Common Denominator

1. Definition
Rewrite fractions with different denominators as equivalent fractions sharing a denominator.
2. Formula & Notation
Common denominatorUsually the least common multiple
Equivalent fractionsMultiply top and bottom alike
3. Properties & Laws
  • Use the least common multiple;
  • Multiply numerator too;
  • Value unchanged;
  • Basis for adding and comparing.
4. Steps
  1. Enter two fractions;
  2. Click "Rewrite";
  3. Or click "Load Example".
5. Worked Examples
Example: 1/6 and 3/8.
Solution: LCD 24, giving 4/24 and 9/24.
6. Common Pitfalls
Multiply the numerator;
Not simplifying;
Denominators positive.

❓ FAQ | Common Denominator

Common denominator?
Shared denominator, value unchanged.
1/6 and 3/8?
4/24 and 9/24.
Find it?
Least common multiple.
Vs simplify?
Rewrite enlarges; simplify reduces.
Use?
Add, subtract, compare.
Numerator?
Multiply it too.