Overview
Enter two or more positive whole numbers, separated by commas, to find their least common multiple - the smallest positive number that all of them divide into evenly. Computed using the standard GCD-based method (LCM(a, b) = |a × b| / GCD(a, b)), applied pairwise across however many numbers you enter, so this works for two numbers or a longer list just as easily. Useful for adding fractions with different denominators, scheduling problems where events repeat at different intervals, or checking schoolwork. Runs entirely client-side.
Best for: Finding a common denominator when adding or comparing fractions
How to use this tool
- Enter your numbers. Two or more positive whole numbers, separated by commas.
- LCM is computed instantly. Calculated pairwise using the GCD-based method, so any count of numbers works.
- Read the result. The least common multiple updates live as you edit the list.
Frequently asked questions
The LCM is computed pairwise: the LCM of the first two numbers is found, then that result is combined with the third number, and so on. This is mathematically equivalent to finding the LCM of all numbers at once and works for any count of inputs.
LCM is only defined for positive whole numbers, so negative numbers, zero, and decimals are rejected with a clear message rather than producing a nonsensical result.