Java Program for Automorphic Number

Problem: Write a Java program to check whether a given number is an Automorphic number or not.

An Automorphic number is that number whose square ends in the same digits as the number itself.

Examples: 25, 76, 376, etc.

Steps to Check Automorphic Number in Java

1. Input a number (num).
2. Square the number (sqr).
3. Count the number of digits of (num) using while loop (c).
4. Compare the last (c) digits of (sqr) with the (num).
5. If they are equal then the number is Automorphic else not.

Check Whether a number is an Automorphic Number in Java

import java.util.Scanner;
 
public class Automorphic {
 
    public static void main(String args[]){
 
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a number");
        int num = in.nextInt();
 
        int c=0, sqr = num*num;
        int temp =num;  //copying num
 
        //countint digits of num
        while(temp>0){
            c++;
            temp=temp/10;
        }
 
        int lastSquareDigits = (int) (sqr%(Math.pow(10,c)));
 
        if(num == lastSquareDigits)
            System.out.println("Automorphic number");
        else
            System.out.println("Not an Automorphic number");
    }
}

Output:

Enter a number
376
Automorphic number

Enter a number
22
Not an Automorphic number

Java Program to Find all Automorphic Numbers in the Interval

Using the above program we can only check a single number, whether it is Automorphic or not.

To check and find all automorphic numbers in a given range, we need to define a function that will return true or false based on whether the number passed as parameter is automorphic or not.

Using a loop, we will iterate through all the numbers in the given interval and call the function for each number as an argument.

import java.util.Scanner;
 
public class Automorphicrange {
 
    public static void main(String args[]){
        Scanner in = new Scanner(System.in);
 
        int l, h;
 
        System.out.println("Input lower interval value");
        l = in.nextInt();
        System.out.println("Input upper interval value");
        h = in.nextInt();
 
        System.out.println("Automorphic numbers between "+l+" and "+h);
        for(int i=l; i<=h; i++){
            if(checkAutomorphic(i))
                System.out.print(i+" ");
        }
    }
 
    private static boolean checkAutomorphic(int num) {
        int c=0, sqr = num*num;
        int temp =num;  //copying num
 
        //countint digits of num
        while(temp>0){
            c++;
            temp=temp/10;
        }
 
        int lastSquareDigits = (int) (sqr%(Math.pow(10,c)));
 
        return num == lastSquareDigits;
    }
}

Output:

Input lower interval value
1
Input upper interval value
100
Automorphic numbers between 1 and 100
1 5 6 25 76

Any Doubts comment below.