About this tool
Enter two or more whole numbers to find their greatest common divisor (GCD) and least common multiple (LCM). It uses BigInt and the Euclidean algorithm, so very large integers stay exact — all in your browser.
Frequently asked questions
How many numbers can I enter?
At least two are required, but you can enter as many as you like — the GCD and LCM are computed across the whole list.
How are they computed?
The GCD uses the Euclidean algorithm; the LCM is derived as a divided by the GCD, times b, reduced across all numbers using exact BigInt math.