NEON Number - Java

A neon number is a number where the sum of digits of the square of the number is equal to the number.

Example: 0,1 and 9

Say for example, if you have 9 then square of 9 is 81.

8+1 = 9

As it can be seen that sum of digits of the square of the number is equal to the number. Hence, it is a NEON number.

Let's see the Java program to determine if a number is NEON Number or not.

import java.util.Scanner;

class NEON

{

    public static void main(String[]args)

    {

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter a number");

        int n = sc.nextInt();

        int sum = 0,temp = n, square;

        square = n*n;

        while(square!=0)

        {

            sum+=square%10;

            square/=10;

        }

        if(sum == n)

        {

            System.out.println("It is a NEON number");

        }

        else

        {

            System.out.println("It is not a NEON number");

        }

    }

}

Demonstration:

1. First, Scanner class is imported.
2. A class namely NEON have been defined.
3. A main method have been defined.
4. Object of Scanner class have been created.
5. A Number has been demanded from user by giving a message.
6. To accept and store the number, a variable namely n has been defined of int data type

7. Then, three different variables namely

    a) sum - This variable will store the sum of digits in the variable square. First, it is initialized with 0.

    b) temp - This variable will hold the number given by user on temporary basis.

    c) square - This variable will store the square of the number given by user.

Now, let us see the working:

square = n*n;

This above operation will evaluate the square of the number given by user. Say for example, user gave 9. Here, first square of 9 will be evaluated using this statement.

while(square!=0)

This loop will continue its iteration until value of square doesn't become equals to 0.

Square of 9 is 81. So, first 1 will be extracted, then 8 will get extracted as it is in index 0. Refer to the below diagram for clear understanding.

sum+ = square%10;

Here, we need to understand few things.

First, individual digits from number is getting extracted using square%10.

As in case of 81, the first extracted number using square%10 will be 1.

Then, this number will get added to the variable sum.

Similarly, second number using square%10 will be 8 and it will also be added to sum.

Now, sum is containing 1+8 = 9

square/=10;

In previous operation, we have seen that the first extracted number using square%10 was 1. Immediately, after this operation, square/=10; will be executed which means 81 is now going to be divided by 10 resulting to 8.1. This operation will permanently delete this 1 from square variable. so that in next iteration, 1 doesn't gets added to the sum variable again. Like this, it will keep on deleting the digits from square variable.

Here is the final outcome:

sum is now containing sum of square of number i.e. 8+1 = 9

n variable is containing the number i..e 9

Finally, with the conditional statement using if-else, it is determined if sum is equal to n or not as it can be seen in the program. If sum is equal to n, then it is displaying that the number is a NEON number. Otherwise, it is displaying that the number is not a NEON number.

Now, write this program and test it with various numbers and increase your knowledge.

Happy Coding.......