# Java Program to Find GCD of two Numbers

## What are GCD?

In this Article, we will write a program to find GCD of two numbers in Java.
GCD stands for Greatest Common Divisor, also known as Highest Common Factor (HCF). It is the largest positive integer that divides two or more integers without leaving a remainder.

### Program to Find GCD of Two Numbers Using For Loop:

Run
```import java.util.*;

public class Main{
public static void main(String[] args) {
// Taking input of two numbers
Scanner scn = new Scanner(System.in);
int num1 = scn.nextInt();
int num2 = scn.nextInt();

// int n1 = 81, n2 = 153;

// initializing answer variable
int gcd = 1;

for (int i = 1; i <= num1 && i <= num2; i++){
if (num1 % i == 0 && num2 % i == 0)
gcd = i;
}
System.out.println("GCD of " + num1 +" and " + num2 + " is " + gcd);
}
}
```
```Output:

GCD of 81 and 153 is 9```

### Program to Find GCD of Two Numbers Using while Loop:

Run
```import java.util.*;

public class Main{
public static void main(String[] args) {
// Taking input of two numbers
Scanner scn = new Scanner(System.in);
int num1 = scn.nextInt();
int num2 = scn.nextInt();

int temp1 = num1;
int temp2 = num2;
// loop to calculate GCD of two numbers
while(num1 != num2) {
if(num1 > num2) {
num1 -= num2;
}
else {
num2 -= num1;
}
}
System.out.println("GCD of " + temp1 +" and " + temp2 + " is " + num1);
}
}
```
```Output:

GCD of 81 and 153 is 9```

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