Common Denominator Calculator

Your details

Enter a fraction (3/4), mixed number (1 2/3), or whole number. Denominator cannot be 0.
Enter a second fraction, mixed number, or whole number.
Optional third fraction. Leave blank to calculate for only two fractions.
Optional fourth fraction.
Choose which calculation method to display in the step-by-step panel.
Least Common Denominator
15

The smallest positive integer that all entered denominators divide evenly into.

Fraction 1 (LCD form)5/15
Fraction 2 (LCD form)6/15
Denominators used3, 5
Fractions entered2
LCD15
Fractions2

The least common denominator is 15.

  • The LCD 15 is the smallest number divisible by all 2 denominators (3, 5).
  • Rewrite your fractions with denominator 15: 5/15 and 6/15.
  • Once fractions share the same denominator you can add or subtract their numerators directly.
  • After adding or subtracting, simplify the result by dividing numerator and denominator by their GCD.

Next stepTo add fractions with unlike denominators: find the LCD, rewrite each fraction, add the numerators, then simplify.

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