GCF & LCM Calculator
Free online GCF and LCM calculator. Find the Greatest Common Factor (GCF, GCD, HCF) and Least Common Multiple (LCM) of two or more numbers with prime factorization. Uses Euclid’s algorithm. 100% client-side.
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What is GCF & LCM Calculator?
The GCF & LCM Calculator is a free, browser-based tool that finds the Greatest Common Factor (GCF, also known as GCD or HCF) and the Least Common Multiple (LCM) of two or more positive integers. It uses the efficient Euclidean algorithm and also displays the prime factorization of each input number, so you can verify the results by hand. Everything runs locally in your browser, making it safe for homework, teaching, and number-theory work.
Key Benefits
- Find GCF and LCM of any number of positive integers in one step
- Uses the fast Euclidean algorithm for instant results with large numbers
- Shows prime factorization of each input for easy verification
- Detects coprime (relatively prime) number sets automatically
- 100% client-side — your numbers never leave your browser
Common Use Cases
- •Simplify fractions by dividing numerator and denominator by their GCF
- •Find a common denominator for adding or subtracting fractions using the LCM
- •Solve number-theory homework and verify GCF/LCM by checking prime factorizations
- •Determine if two numbers are coprime for cryptography or modular arithmetic
- •Synchronize repeating events by finding the LCM of their cycle lengths
How to Use the GCF & LCM Calculator
- Enter Your Numbers: Type or paste two or more positive integers into the input box. Separate them with commas, spaces, semicolons, or new lines — for example, 12, 18, 24.
- View the Results: The calculator instantly displays the GCF (Greatest Common Factor) and LCM (Least Common Multiple) in two highlighted result cards.
- Check the Prime Factorization: Below the results, each input number is broken down into its prime factors with exponent notation so you can verify the answer by hand.
- Copy or Clear: Click Copy to copy the GCF and LCM to your clipboard, or click Clear to start over with a new set of numbers.
Key Features
- Calculates GCF (GCD, HCF) and LCM simultaneously for any quantity of positive integers
- Uses the fast Euclidean algorithm to handle very large numbers instantly
- Shows the prime factorization of each input number with exponent notation
- Detects and highlights coprime (relatively prime) number sets automatically
- Accepts input separated by commas, spaces, semicolons, or new lines
- 100% client-side — your numbers never leave your browser, no signup required