# C Exercises: Determine the LCM of two numbers using HCF

## C For Loop: Exercise-44 with Solution

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

The task is to write a C program that calculates the Least Common Multiple (LCM) of two given numbers using their Highest Common Factor (HCF). The program should implement the relationship between LCM and HCF, given by the formula: LCM(a, b) = (a * b) / HCF(a, b).

**Visual Presentation:**

**Sample Solution:**

**C Code:**

```
#include <stdio.h> // Include the standard input/output header file.
void main()
{
int i, n1, n2, j, hcf = 1, lcm; // Declare variables to store input and results.
printf("\n\n LCM of two numbers:\n "); // Print a message.
printf("----------------------\n"); // Print a separator.
printf("Input 1st number for LCM: "); // Prompt the user for input.
scanf("%d", &n1); // Read the first number from the user.
printf("Input 2nd number for LCM: "); // Prompt the user for input.
scanf("%d", &n2); // Read the second number from the user.
j = (n1 < n2) ? n1 : n2; // Determine the smaller of the two numbers.
// Loop to find the highest common factor (HCF).
for(i = 1; i <= j; i++)
{
if(n1 % i == 0 && n2 % i == 0)
{
hcf = i; // Update the HCF whenever a common factor is found.
}
}
// Calculate the least common multiple (LCM).
lcm = (n1 * n2) / hcf;
// Print the result.
printf("\nThe LCM of %d and %d is : %d\n\n", n1, n2, lcm);
}
```

Output:

LCM of two numbers: ---------------------- Input 1st number for LCM: 15 Input 2nd number for LCM: 20 The LCM of 15 and 20 is : 60

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