# Greatest Common Divisor & Least Common Multiple Calculator

First Number: Second Number:
Third Number (not required):

Greatest Common Factor (GCF):
Least Common Multiplier (LCM):

Greatest Common Divisor & Least Common Multiple Calculator: This calculator can quickly determine the Greatest Common Factor and Least Common Multiplier between two or three numbers.

## What is the Least Common Multiple LCM?

The Least Common Multiple (LCM) of two or more numbers is the Least non-zero natural number that is both a multiple of all of those numbers.

If one of the numbers for which we are looking for the least common multiple is zero, then the LCM of these numbers is zero.

## How to find the least common multiple LCM?

Method 1: multiples

As we are looking for the least common multiple, we can simply list the multiples of the numbers studied and locate the multiple common to these numbers which is the smallest. This simple method is especially suitable when you have small numbers.

Method 2: The table of prime divisors

This method consists in simultaneously dividing the numbers whose LCM we are looking for by prime divisors. The LCM will then be the product of these prime dividers. Please note, the method is slightly different from that presented for the GCD. This method is useful when looking for the LCM between two large numbers.

Method 3: The factor tree

This method consists of doing the first factorization of all the numbers for which we are looking for the LCM. The LCM will be made up of common factors and factors that are not common. This method is very versatile.

## What is the Greatest Common Divisor GCD?

The Greatest Common Divisor (GCD) between two or more numbers is the largest natural number that divides all of those numbers simultaneously.

When two or more numbers have a GCD equal to 1, these numbers will be said to be prime to each other or co-prime.

## How to find the greatest common divisor GCD?

Method 1: the dividers

As we are looking for the greatest common divisor, we can simply list the divisors of the numbers studied and locate the greatest of the divisors common to these numbers. This simple method is especially suitable when you have small numbers.

Method 2: the table of prime divisors

This method consists of simultaneously dividing the studied numbers by prime divisors. The GCD will then be the product of these prime dividers. This method is faster and more efficient when looking for the GCD between two large numbers.

Method 3: prime factors

This method consists of doing the first factorization of all the numbers and writing the GCD as a common product of the factors.