In this program, we will learn to code the **Java Program to Find GCD of Two Numbers**. Let’s understand more about **GCD** or **Greatest Common Divisor** and** How to calculate the GCD of Two Numbers. **

We will calculate the GCD of two numbers using the following approaches:

- Using For Loop
- Using While Loop

Now, let’s see the Java Program to Find GCD of Two Numbers Using For Loop.

**Java Program to Find GCD of Two Numbers**

import java.util.*; public class Main{ public static void main(String[] args){ Scanner sc = new Scanner(System.in); System.out.println("Enter first number: "); int first = sc.nextInt(); System.out.println("Enter second number: "); int second = sc.nextInt(); int gcd=0; // Calculating GCD of two numbers for (int i = 1; i <= first && i <= second; i++){ if (first % i == 0 && second % i == 0){ gcd = i; } } System.out.println("GCD of "+first+" and "+second+" is "+gcd); } }

**Output**

`Enter first number: `**10**
Enter second number: **25**
**GCD of 10 and 25 is 5**

**How Does This Program Work ?**

Scanner sc = new Scanner(System.in); System.out.println("Enter first number: "); int first = sc.nextInt(); System.out.println("Enter second number: "); int second = sc.nextInt();

In this program, we have taken the input of both numbers to find the GCD using the Scanner Class in Java.

// Calculating GCD of two numbers for (int i = 1; i <= first && i <= second; i++){ if (first % i == 0 && second % i == 0){ gcd = i; } }

Then, we used **for loop** to calculate the gcd of two numbers. If the iteration of * i* is divisible by both the first number as well as the second number, then it is a factor of both numbers.

The value of **i** keeps increasing until it is equal to either ‘**first**‘ or ‘**second**‘. The highest factor computed is the gcd of two numbers. The GCD of two numbers gets stored in the **gcd** named variable.

System.out.println("GCD of "+first+" and "+second+" is "+gcd);

Then, we have just displayed the GCD calculated using the

function in Java.**System.out.println()**

This is the **Java Program to Find the GCD of Two Numbers Using For Loop**. Now, let’s see the **Java program to find the GCD of Two Numbers using While loop.**

**Java Program to Find GCD of Two Numbers Using While Loop**

import java.util.*; public class Main{ public static void main(String[] args){ Scanner sc = new Scanner(System.in); System.out.println("Enter first number: "); int first = sc.nextInt(); System.out.println("Enter second number: "); int second = sc.nextInt(); int gcd=0; // Calculating gcd using while loop while (second != 0){ int temp = second; second = first % second; first = temp; } gcd = first; System.out.println("The GCD is "+gcd); } }

**Output**

`Enter first number: `**21**
Enter second number: **28**
**The GCD is 7**

**Conclusion**

I hope after going through this post, you understand the **Java Program to Find GCD of Two Numbers**.

If you have any doubt regarding the topic, feel free to contact us in the Comment Section. We will be delighted to help you.

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