LCM of Two Numbers

Program to find Least Common Multiple of two numbers

IntermediateTopic: Loop Programs
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C++ LCM of Two Numbers Program

This program helps you to learn the fundamental structure and syntax of C++ programming.

Try This Code
#include <iostream>
using namespace std;

int main() {
    int a, b, gcd, lcm;
    
    cout << "Enter two numbers: ";
    cin >> a >> b;
    
    int originalA = a, originalB = b;
    
    // Find GCD first
    while (b != 0) {
        int temp = b;
        b = a % b;
        a = temp;
    }
    gcd = a;
    
    // LCM = (a * b) / GCD
    lcm = (originalA * originalB) / gcd;
    
    cout << "LCM of " << originalA << " and " << originalB << " is: " << lcm << endl;
    
    return 0;
}
Output
Enter two numbers: 12 18
LCM of 12 and 18 is: 36

Understanding LCM of Two Numbers

LCM (Least Common Multiple) is calculated using the relationship: LCM(a, b) = (a × b) / GCD(a, b). We first find the GCD using the Euclidean algorithm, then use it to calculate the LCM. This is more efficient than checking multiples.

Note: To write and run C++ programs, you need to set up the local environment on your computer. Refer to the complete article Setting up C++ Development Environment. If you do not want to set up the local environment on your computer, you can also use online IDE to write and run your C++ programs.

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GCD of Two Numbers
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