Calculator Tools
GCD & LCM Calculator
Find the Greatest Common Divisor (GCD) and Lowest Common Multiple (LCM) of two or more numbers with full step-by-step working using the Euclidean algorithm and prime factorisation.
Features
- GCD and LCM calculated simultaneously
- Supports 2 to 10 numbers at once
- Step-by-step Euclidean algorithm shown for GCD
- Prime factorisation shown for LCM
- Works with large numbers
- Shows factors and prime factors for each input
- No account, browser-only
How to use it
- Enter two or more integers (separated by commas or spaces).
- GCD and LCM are calculated instantly.
- Expand 'Show working' to see the Euclidean algorithm steps.
- View prime factorisation for each input number.
Use cases
- Simplifying fractions (GCD of numerator and denominator)
- Finding common scheduling intervals (LCM)
- Mathematics coursework and number theory
- Solving problems involving ratios and proportions
Limitations
- Browser processing depends on available device memory for very large inputs.
- Tool-specific limits based on file format or browser support are noted on each tool page.
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Use toolFrequently asked
What is the GCD?
The Greatest Common Divisor (also called HCF) is the largest number that divides all inputs without a remainder. E.g. GCD(12, 18) = 6.
What is the LCM?
The Lowest Common Multiple is the smallest number divisible by all inputs. E.g. LCM(4, 6) = 12. Used when adding fractions with different denominators.