# 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*.