Find automorphic number in java

In this post, we will see how to find automorphic number in java.
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Automorphic number are those natural numbers whose square ends in same digits are number itself.

Find automorphic number using digits

Here is simple algorithm to find automorphic number using digits.

• Take value of n from user using Scanner class
• Find square of n sqrOfN
• Count number of digits noOfDigits in n
• Find last noOfDigits of sqrOfN and assign it to lastNDigitsOfSquare
• Check if lastNDigitsOfSquare is equal to n
  • If yes, then number is automorphic
  • If no, then number is not automorphic

package org.arpit.java2blog;

import java.util.Scanner;

public class AutomorphicNumberMain {

    public static void main(String args[]){

        Scanner in = new Scanner(System.in);
        System.out.println("Enter a number");
        int n = in.nextInt();

        boolean isAutomorphicNumber = isAutomorphicNumber(n);
        if(isAutomorphicNumber)
        {
            System.out.println(n +" is automorphic number");
        }
        else
        {
            System.out.println(n +" is not automorphic number");
        }
    }

    private static boolean isAutomorphicNumber(int n) {
        int noOfDigits=0;
        int sqrOfN = n * n;
        System.out.println("Square of n is: "+sqrOfN);
        int temp = n;  //copying num

        // count digits of num
        while(temp>0){
            noOfDigits++;
            temp=temp/10;
        }

        int lastNDigitsOfSquare = (int) (sqrOfN%(Math.pow(10,noOfDigits)));

        if(n == lastNDigitsOfSquare)
            return true;
        else
           return false;
    }
}

Output:

Find automorphic number using String

We can also use String’s endsWith() method to find automorphic number using String.
Here is simple algorithm to find automorphic number using digits.

• Take value of n from user using Scanner class and convert it to String numStr
• Find square of n and convert it to String sqrNumStr
• Check if sqrNumStr with numStr
  • If yes, then number is automorphic
  • If no, then number is not automorphic

package org.arpit.java2blog;

import java.util.Scanner;

public class AutomorphicNumberUsingString {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        System.out.println("Enter a number");
        int n = in.nextInt();

        boolean isAutomorphicNumber = isAutomorphicNumberUsingString(n);
        if(isAutomorphicNumber)
        {
            System.out.println(n +" is automorphic number");
        }
        else
        {
            System.out.println(n +" is not automorphic number");
        }
    }

    // Check automorphic number using String
    public static boolean isAutomorphicNumberUsingString(int n) {

        // convert numbers to string
        String numStr = Integer.toString(n);
        String sqrNumStr = Integer.toString(n*n);
        System.out.println("Square of n is: "+sqrNumStr);
        // check endWith
        if(sqrNumStr.endsWith(numStr))
            return true;

        return false;
    }
}

Output:

Find automorphic number in range

We can simply use a for loop to iterate from minimum to maximum range interval and check if number is automorphic or not.

package org.arpit.java2blog;

import java.util.Scanner;

public class AutomorphicNumberRange {

    public static void main(String[] args) {
        int min = 0, max = 0;

        Scanner scanner = new Scanner(System.in);

        // Get min and max values
        System.out.print("Enter minimum range: ");
        min = scanner.nextInt();
        System.out.print("Enter maximum range ");
        max = scanner.nextInt();

        // check number
        System.out.println("The Automorphic numbers from "+
                min+" to "+ max+" are: ");

        for(int i=min; i<=max; i++) {
            if(isAutomorphicNumber(i))
                System.out.print(i+" ");
        }

        // close Scanner class object
        scanner.close();
    }

    private static boolean isAutomorphicNumber(int n) {
        int noOfDigits=0;
        int sqrOfN = n * n;
        int temp = n;  //copying num

        // count digits of num
        while(temp>0){
            noOfDigits++;
            temp=temp/10;
        }

        int lastNDigitsOfSquare = (int) (sqrOfN%(Math.pow(10,noOfDigits)));

        if(n == lastNDigitsOfSquare)
            return true;
        else
            return false;
    }
}

Output:

That’s all about how to find automorphic number in java.