C++ Exercises: Find LCM of any two numbers using HCF

Last update on April 07 2025 12:59:37 (UTC/GMT +8 hours)

29. Find the LCM of Two Numbers Using HCF

Write a program in C++ to find the LCM of any two numbers using HCF.

Visual Presentation:

C++ Exercises: Find LCM of any two numbers using HCF

Sample Solution:-

C++ Code :

#include <iostream> // Including input-output stream header

using namespace std; // Using standard namespace to avoid writing std::

int main() // Start of the main function
{
    int i, n1, n2, j, hcf = 1, lcm; // Declaration of integer variables: 'i' (loop counter), 'n1' and 'n2' (input numbers), 'j' (temporary variable), 'hcf' (stores the HCF), 'lcm' (stores the LCM)

    cout << "\n\n LCM of two numbers:\n"; // Displaying a message on the console
    cout << "------------------------\n";
    cout << " Input 1st number for LCM: "; // Asking the user for the 1st number
    cin >> n1; // Reading the 1st number from the user
    cout << " Input 2nd number for LCM: "; // Asking the user for the 2nd number
    cin >> n2; // Reading the 2nd number from the user

    j = (n1 < n2) ? n1 : n2; // Determining the smaller of the two numbers

    for (i = 1; i <= j; i++) { // Loop to find the Highest Common Factor (HCF)
        if (n1 % i == 0 && n2 % i == 0) { // Checking if 'i' is a common factor of both numbers
            hcf = i; // Updating the HCF when 'i' is a common factor
        }
    }

    /* mltiplication of HCF and LCM = the multiplication of these two numbers.*/
    lcm = (n1 * n2) / hcf; // Calculating the Least Common Multiple (LCM) using the formula LCM * HCF = Product of the numbers

    cout << " The LCM of " << n1 << " and " << n2 << " is: " << lcm << endl; // Displaying the calculated LCM
}

Sample Output:

 LCM of two numbers:                                                   
------------------------                                               
 Input 1st number for LCM: 15                                          
 Input 2nd number for LCM: 25                                          
 The LCM of 15 and 25 is: 75

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to compute the LCM of two numbers by first calculating their GCD using Euclid’s algorithm.
Write a C++ program that reads two numbers and computes their least common multiple via the formula LCM = (a*b)/GCD(a, b).
Write a C++ program to find the LCM of two integers using a while loop to search for the smallest common multiple.
Write a C++ program that implements both recursive GCD and iterative LCM calculations for two input numbers.

C++ Code Editor:

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