The Program in C# Program to find LCM of two numbers using HCF is given below:

using System;

namespace LCM_HCF
{
    class Program
    {
        static void Main(string[] args)
        {
            int num1, num2, hcf, lcm;
Console.WriteLine("Hello Codeauri Family,enter first and second numbers below to find lcm : ");
            Console.Write("Well,enter the first number: ");
            num1 = Convert.ToInt32(Console.ReadLine());
            Console.Write("Well, enter the second number: ");
            num2 = Convert.ToInt32(Console.ReadLine());

            hcf = HCF(num1, num2);
            lcm = num1 * num2 / hcf;

            Console.WriteLine("Okay, The LCM of " + num1 + " and " + num2 + " is " + lcm);
            Console.ReadLine();
        }

        static int HCF(int n1, int n2)
        {
            int remainder;

            while (n2 != 0)
            {
                remainder = n1 % n2;
                n1 = n2;
                n2 = remainder;
            }

            return n1;
        }
    }
}

Output:

Hello Codeauri Family,enter first and second numbers below to find lcm :
Well,enter the first number: 5
Well, enter the second number: 10
Okay, The LCM of 5 and 10 is 10

Pro-Tips💡

Here are the step by step execution of above program:

1. using System; – This line is a using directive, which tells the compiler to use the System namespace, which includes classes and methods used in the program.
2. namespace LCM_HCF – The namespace declaration creates a namespace named LCM_HCF to group classes and other code elements in a logical and organized manner.
3. class Program – This is a class declaration, creating a class named Program.
4. static void Main(string[] args) – This is the main method of the program, the entry point for the program. When the program is executed, the code inside the Main method is executed first.
5. int num1, num2, hcf, lcm; – This line declares four integer variables: num1, num2, hcf, and lcm.
6. Console.WriteLine("Hello Codeauri Family,enter first and second numbers below to find lcm : "); – This line writes a message to the console asking the user to enter two numbers.
7. Console.Write("Well,enter the first number: "); – This line writes a message to the console asking the user to enter the first number.
8. num1 = Convert.ToInt32(Console.ReadLine()); – This line reads the first number entered by the user, converts it to an integer using the Convert.ToInt32 method, and assigns it to the num1 variable.
9. Console.Write("Well, enter the second number: "); – This line writes a message to the console asking the user to enter the second number.
10. num2 = Convert.ToInt32(Console.ReadLine()); – This line reads the second number entered by the user, converts it to an integer using the Convert.ToInt32 method, and assigns it to the num2 variable.
11. hcf = HCF(num1, num2); – This line calls the HCF method and assigns the result to the hcf variable.
12. lcm = num1 * num2 / hcf; – This line calculates the LCM by multiplying num1 and num2 and dividing the result by the hcf. The result is assigned to the lcm variable.
13. Console.WriteLine("Okay, The LCM of " + num1 + " and " + num2 + " is " + lcm); – This line writes the result to the console.
14. Console.ReadLine(); – This line waits for the user to press enter before ending the program.
15. static int HCF(int n1, int n2) – This method calculates the HCF of two numbers.
16. int remainder; – This line declares an integer variable remainder.
17. while (n2 != 0) – This line starts a while loop that will run as long as n2 is not equal to 0.
18. remainder = n1 % n2; – This line calculates the remainder when n1 is divided