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LCM & GCD Calculator

Least common multiple and greatest common divisor.

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About the LCM & GCD Calculator

Find the least common multiple (LCM) and greatest common divisor (GCD, also called HCF) of two or more numbers, with the prime-factor method shown.

Example

For 12 and 18: GCD = 6, LCM = 36. Check: GCD × LCM = 12 × 18 = 216.

LCM is used to add fractions with different denominators; GCD to simplify them.

How to use LCM & GCD Calculator

  1. Enter your values. Units and defaults are shown beside each field.
  2. Press Calculate (results also update as you type once calculated).
  3. Read the result and the step-by-step breakdown with the formula used.
  4. Copy the result or reset to start again.

Frequently asked questions

How accurate is this calculator?

Calculations use the standard formulas shown on the page, computed in full precision and rounded only for display. The result is only as accurate as the inputs and assumptions listed.

Is it free?

Yes. All tools are free to use without an account.

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