**A program to calculate GCD(greatest common divisor) of two numbers:-**

The **greatest common divisor** (**gcd**) of two or more integers, is the largest positive integer that divides each of the integers. For example, the **gcd** of 8 and 12 is 4.

import java.util.*;

class gcd{

public static void main(){

Scanner sc=new Scanner(System.in);

System.out.println(“Enter 2 numbers:”);

int a=sc.nextInt();

int b=sc.nextInt();

System.out.println(“\n ****Calculating GCD****\n”);

int t=0;

if(a>b){

t=a;

a=b;

b=t;

}

if(a==0){

System.out.println(“GCD:”+a);

b=0;

}

while(b!=0){

t=0;

if(b%a==0){

System.out.println(“GCD:”+a);

break;

}

else{

t=b%a;

b=a;

a=t;

}

}

}

}

output:-

Enter 2 numbers

12 8

****Calculating GCD****

GCD 4

**2. Automorphic Number:-**

An **automorphic number** is a **number** whose square “ends” in the same digits as the **number** itself. For example, 5^{2} = 25, 6^{2} = 36

import java.util.*;

class automorphic{

public static void main(){

Scanner sc=new Scanner(System.in);

System.out.println(“Enter a number:”);

int n=sc.nextInt();

double sq=Math.pow(n,2);

int t=n,c=0,d=0;

while(t>0){

d=t%10;

c=c+1;;

t/=10;

}

double s=Math.pow(10,c);

int r=(int)sq%(int)s;

if(r==n){

System.out.println(“It is automorphic.”);

}

else{

System.out.println(“Not automorphic.”);

}

}

}

**output:- **

Enter a number:

6

It is automorphic