# C++ Program to Find LCM of Two Numbers

In this post, we will learn how to find the lcm of two numbers using C++ Programming language.

The LCM (Least Common Multiple) of two numbers a and b is the smallest positive integer that is perfectly divisible by both a and b.

We will be finding the lcm of two numbers using the following ways:

1. Using Standard Method
2. Using GCD

So, without further ado, let’s begin this tutorial.

## C++ Program to Find LCM of Two Numbers

```// C++ Program to Find LCM of Two Numbers
#include <iostream>
using namespace std;

int main(){
int a, b, lcm;

cout << "Enter the first number: ";
cin >> a;
cout << "Enter the second number: ";
cin >> b;

lcm = (a > b) ? a : b; //greatest of the two

while(1){
if ((lcm % a == 0) && (lcm % b == 0)){
cout << "LCM of two numbers: " << lcm;
break;
}
++lcm;
}
return 0;
}
```

Output

``````Enter the first number: 12
Enter the second number: 15
LCM of two numbers: 60
``````

## How Does This Program Work ?

```    int a, b, lcm;
```

In this program, we have declared three int data type variables named a, b and lcm.

```    // Asking for input
cout << "Enter the first number: ";
cin >> a;
cout << "Enter the second number: ";
cin >> b;
```

Then, the user is asked to enter two integers. The value of these two integers will get stored in a and b named variables.

```    while(1){
if ((lcm % a == 0) && (lcm % b == 0)){
cout << "LCM of two numbers: " << lcm;
break;
}
++lcm;
}
```

Now, we check whether the maximum value is divisible by both a and b or not. If yes, then the value of lcm variables is printed and our program terminates.

If not, then lcm is incremented by 1 and the same process goes on until lcm is exactly divisible by both a and b.

## C++ Program to Find LCM of Two Numbers Using HCF

```// C++ Program to Find the LCM of Two Numbers Using HCF
#include <iostream>
using namespace std;

int main(){
int a, b, i, gcd, lcm;

cout << "Enter the first number: ";
cin >> a;
cout << "Enter the second number: ";
cin >> b;

// Calculating GCD
for (i = 1; i <= a && i <= b; ++i){
if (a % i == 0 && b % i == 0)
gcd = i;
}

// Calculating lcm using hcf
lcm = (a * b) / gcd;
cout << "LCM of two numbers: " << lcm << endl;
return 0;
}
```

Output

``````Enter the first number: 3
Enter the second number: 5
LCM of two numbers: 15
``````

## Conclusion

I hope after going through this post, you understand how to find the lcm of two numbers using C++ Programming language.

If you have any doubt regarding the program, feel free to contact us in the comment section. We will be delighted to assist you.