Java Program to Find LCM of Two Numbers

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LCM (i.e. Least Common Multiple) is the largest of the two stated numbers that can be divided by both the given numbers.

Example for LCM of Two Numbers

Input: LCM( 15 and 25)
Output: 75

Input: LCM( 3 and 7 )
Output: 21

Methods to Find LCM

There are certain methods to Find the LCM of two numbers as mentioned below:

Using if statement
Using GCD

1. Using if statement to Find the LCM of Two Numbers

Using if is a really simple method and also can be said brute force method.

Below is the implementation of the above method:

Java

// Java Program to find
// the LCM of two numbers
import java.io.*;
 
// Driver Class
class GFG {
    // main function
    public static void main(String[] args)
    {
        // Numbers
        int a = 15, b = 25;
 
        // Checking for the smaller
        // Number between them
        int ans = (a > b) ? a : b;
 
        // Checking for a smallest number that
        // can de divided by both numbers
        while (true) {
            if (ans % a == 0 && ans % b == 0)
                break;
            ans++;
        }
 
        // Printing the Result
        System.out.println("LCM of " + a + " and " + b
                           + " : " + ans);
    }
}

Output

LCM of 15 and 25 : 75

2. Using Greatest Common Divisor

Below given formula for finding the LCM of two numbers ‘u’ and ‘v’ gives an efficient solution.

u x v = LCM(u, v) * GCD (u, v)
LCM(u, v) = (u x v) / GCD(u, v)

Here, GCD is the greatest common divisor.

Below is the implementation of the above method:

Java

// Java program to find LCM
// of two numbers.
class gfg {
    // Gcd of u and v
    // using recursive method
    static int GCD(int u, int v)
    {
        if (u == 0)
            return v;
        return GCD(v % u, u);
    }
 
    // LCM of two numbers
    static int LCM(int u, int v)
    {
        return (u / GCD(u, v)) * v;
    }
 
    // main method
    public static void main(String[] args)
    {
        int u = 25, v = 15;
        System.out.println("LCM of " + u + " and " + v
                           + " is " + LCM(u, v));
    }
}