Howdy readers, today you will learn **how to write a program to find the gcd and lcm of two numbers using the C** Programming language.

The **Greatest Common Divisor (GCD)** of two numbers is the largest possible number which divides both the numbers exactly. For example: The GCD of **15** and **30** is **5**.

The **Least Common Multiple (LCM)** of two or more numbers is the smallest number among all common multiples of the given numbers. For example: The LCM of **2** and **5** is **10**.

In the below program, we compute the gcd using for loop and lcm with the help of below formula.

**LCM(a, b) = (a x b) / GCD(a, b)**

So, without any delay, letâ€™s begin this tutorial.

**C Program to Find GCD and LCM of Two Numbers**

**C Program**

// C Program to Find GCD and LCM of Two Numbers #include <stdio.h> int main(){ int num1, num2, gcd, lcm; // Asking for input printf("Enter the first number: "); scanf("%d", &num1); printf("Enter the second number: "); scanf("%d", &num2); // Calculating the gcd for (int i = 1; i <= num1 && i <= num2; i++){ if (num1 % i == 0 && num2 % i == 0){ gcd = i; } } // Calculating the lcm lcm = (num1 * num2) / gcd; // Displaying result printf("GCD of %d and %d is: %d \n", num1, num2, gcd); printf("LCM of %d and %d is: %d", num1, num2, lcm); return 0; }

**Output**

Enter the first number: 15 Enter the second number: 100 GCD of 15 and 100 is: 5 LCM of 15 and 100 is: 300

**Explanation**

int num1, num2, gcd, lcm;

In the above example, we have declared four int data type variables named ** num1**,

**,**

`num2`

**and**

`gcd`

**.**

`lcm`

// Asking for input printf("Enter the first number: "); scanf("%d", &num1); printf("Enter the second number: "); scanf("%d", &num2);

The user is asked to enter two numbers. These values get stored in the ** num1** and

**named variables.**

`num2`

// Calculating the gcd for (int i = 1; i <= num1 && i <= num2; i++){ if (num1 % i == 0 && num2 % i == 0){ gcd = i; } }

GCD is calculated using ** for loop** statement.

// Calculating the lcm lcm = (num1 * num2) / gcd;

Similarly, the lcm is calculated using the formula** lcm(a, b) = (a x b) / gcd(a, b)**.

// Displaying result printf("GCD of %d and %d is: %d \n", num1, num2, gcd); printf("LCM of %d and %d is: %d", num1, num2, lcm);

The **GCD** and **LCM** calculated above is printed on the screen using **printf()** function.

**Conclusion**

I hope after reading this post, you get to know **how to write a program to find the gcd and lcm of two numbers using the C** Programming language.

If you have any doubt regarding the tutorial, then let us know in the comment section. We will be pleased to solve all of your queries.