Write a C program to enter two numbers and find LCM (Lowest Common Multiple) using for loop. How to find LCM of two given numbers in C programming. Logic to find LCM of two number in C program.

**Example**

**Input**

Input number1: 12 Input number2: 30

**Output**

LCM = 60

## Required knowledge

Basic C programming, If else, Conditional operator, For loop

Read more - Program to check divisibility

### What is LCM (Lowest Common Multiple)?

LCM is the smallest positive integer that exactly divides two or more numbers. For Example

## Logic to find LCM of two numbers

To make things simple and generic, I have divided the logic in four steps. Below is the descriptive logic to find LCM.

- Find maximum between two numbers. Say max contains maximum between two numbers to find lcm. Maximum is used to generate next multiple which must be common to both.
- If max is exactly divisible by both numbers. Then you got your answer, lcm of two numbers is max.
- If you did not got your answer in previous step. Then generate next multiple of max.
- Repeat 2-3 step till lcm is not found.

## Program to find LCM of two numbers

```
/**
* C program to find LCM of any two numbers
*/
#include <stdio.h>
int main()
{
int i, num1, num2, max, lcm=1;
/*
* Input two numbers from user
*/
printf("Enter any two numbers to find LCM: ");
scanf("%d%d", &num1, &num2);
// Find maximum between num1 and num2
max = (num1 > num2) ? num1 : num2;
// First multiple to be checked for common
i = max;
// Loop runs forever till lcm is not found
while(1)
{
if(i%num1==0 && i%num2==0)
{
/*
* If i divides both num1 and num2
* then lcm is found hence exit from loop
*/
lcm = i;
break;
}
/*
* If lcm is not found then generate next
* multiple of max between both numbers
*/
i += max;
}
printf("LCM of %d and %d = %d", num1, num2, lcm);
return 0;
}
```

**Note:** Do not confuse with the statement max = (num1 > num2) ? num1 : num2;. It finds maximum between two numbers.

Must know - Program to find maximum using conditional operator.

Before you move to next exercise or program. I strongly recommend you to learn the program using recursive approach.

Read more - Program to find LCM using recursion.

Output

Enter any two numbers to find LCM: 12 30 LCM of 12 and 30 = 60

Happy coding 😉

<pre><code> ----Your Source Code---- </code></pre>