LCM & GCD Calculator interactive tool
You can paste a list like 6 9 15 or 6,9,15. The calculator will ignore empty entries.
For numbers 12, 18, 30:
GCD is the largest integer that divides all the numbers with no remainder.
LCM is the smallest positive integer that is a multiple of all the given numbers.
What Is LCM & GCD?
An LCM & GCD calculator finds two foundational quantities for a list of integers: the greatest common divisor (GCD) and the least common multiple (LCM). These appear everywhere in fraction problems and divisibility exercises.
Greatest Common Divisor vs. Least Common Multiple
- GCD: The largest integer that divides all the numbers with no remainder.
- LCM: The smallest positive integer that is a multiple of all the numbers.
This LCM and GCD calculator uses efficient algorithms under the hood but presents the results in a simple, readable way, making it ideal for middle school and high school math practice.
How To Use the LCM & GCD Calculator
- Enter two or more integers separated by commas or spaces in the input box.
- Make sure all entries are whole numbers; the LCM and GCD calculator will ignore any blank values.
- Review the greatest common divisor (GCD) for your list of numbers in the results card.
- Review the least common multiple (LCM) shown beneath the GCD to understand the smallest shared multiple.
- Use the Example button to load a common classroom example, or Reset to clear the list and paste your own numbers.
GCD and LCM of multiple numbers
Use this LCM and GCD calculator for two or more integers when you need the greatest common divisor, least common multiple, or both. Enter a list of values to work with common denominators and divisibility problems.
Need the formula or convention behind this result? Read the calculator methods and assumptions.