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

## 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

Before I get deep in the logic to find LCM. You must know how to check divisibility of any number.

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; /* * Read 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. Read more about finding maximum using conditional operator.

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

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

Happy coding ;)

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