The Euclidean algorithm for GCD is over 2,000 years old and still the fastest practical method — this tool runs it instantly on any list of numbers and shows every step along the way.
What Is the GCD & LCM Calculator?
A number-theory tool that computes both the greatest common divisor and least common multiple of two or more integers, reducing the list pairwise and displaying the full Euclidean algorithm trace for the GCD computation.
How to Use It
- Open the tool at /tools/gcd-lcm-calculator.
- Enter two or more whole numbers, separated by commas or spaces.
- Read the GCD, LCM, and full step-by-step trace instantly.
Key Features
- Supports any number of integers, not just pairs, reducing the list pairwise.
- Visible Euclidean algorithm steps, useful for verifying the result by hand or teaching the method.
- LCM derived from GCD using the standard
lcm(a,b) = |a·b| / gcd(a,b)formula. - Fully client-side, nothing ever leaves your browser.
When to Use This Tool
- Simplifying fractions by finding the GCD of numerator and denominator.
- Scheduling problems — finding when repeating events next align (LCM of their periods).
- Math homework and teaching, showing the algorithm’s steps rather than just the final answer.
Try It Now
Open GCD & LCM Calculator directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Math & Numbers collection on WebdevToolbox — free, browser-based developer tools with no login required.