1. Introduction

In this guide, we will develop a Java program to calculate the Least Common Multiple (LCM) of two numbers. The LCM of two integers is the smallest positive integer that is divisible by both numbers. For example, the LCM of 5 and 12 is 60.

2. Program Steps

1. Declare a class named LCMCalculator.

2. Inside this class, define the main method.

3. In the main method, initialize two integer variables with the numbers for which we want to find the LCM.

4. Compute the LCM using the formula: LCM(a, b) = (a * b) / GCD(a, b).

5. Print the calculated LCM.

3. Code Program

public class LCMCalculator { // 1. Declare a class named LCMCalculator

    // Method to find GCD of two numbers
    static int gcd(int a, int b) {
        if (b == 0)
            return a;
        else
            return gcd(b, a % b);
    }

    // Method to find LCM of two numbers using the formula: LCM(a, b) = (a * b) / GCD(a, b)
    static int lcm(int a, int b) {
        return (a * b) / gcd(a, b);
    }

    public static void main(String[] args) { // 2. Define the main method

        int num1 = 15, num2 = 20; // 3. Initialize num1 and num2

        // 4. Compute the LCM
        int lcm = lcm(num1, num2);

        // 5. Print the result
        System.out.println("LCM of " + num1 + " and " + num2 + " is: " + lcm);
    }
}

Output:

LCM of 15 and 20 is: 60

4. Step By Step Explanation

– Step 1: A class named LCMCalculator is declared.

– Step 2: The main method is defined within the class, which is the starting point of our Java program.

– Step 3: We initialize two integer variables, num1 and num2, with the values 15 and 20 respectively.

– Step 4: We calculate the LCM of num1 and num2 using the formula: LCM(a, b) = (a * b) / GCD(a, b). The gcd method is used to find the Greatest Common Divisor (GCD) of the two numbers.

– Step 5: The program prints out the LCM of 15 and 20, which is 60.