Neon Number Program in Java with Examples

In this short tutorial I will be sharing what is Neon number, examples of Neon number, algorithm and program to check whether a given number is Neon number or not.

Read Also : Java Program to Check Magic Number

What is Neon Number

A number is called as  Neon number if sum of digits of the square of the number is equal to the  number.

Examples :

Number to check :  
Square of a given number : 9 * 9 = 81
Sum of digits of square number : 8 + 1 = 9 // 9 is a Neon number
 
Number to check :  
Square of a given number : 1 * 1 = 1
Sum of digits of square number : 1 // 1 is a Neon number

Below are examples of numbers which are NOT Neon numbers

Number to check : 13  
Square of a given number : 13 * 13 = 169
Sum of digits of square number : 1 + 6 + 9 = 16 // 13 is NOT a Neon number
 
Number to check :  
Square of a given number : 8 * 8 = 64
Sum of digits of square number : 6 + 4 = 10 // 8 is NOT a Neon number

List of Neon numbers from 0 to 100 are : 
0, 1, 9

Java Program for Neon Number


import java.util.*;

public class JavaHungry {

    public static void main(String args[]) {
      System.out.println("Enter any number : ");
      Scanner scan = new Scanner(System.in);
      int inputNumber = scan.nextInt();
      boolean result = checkNeonNumber(inputNumber);
      if(result == true)
        System.out.println(inputNumber + " is a Neon number");
      else
        System.out.println(inputNumber + " is NOT a Neon number");     
    }

    public static boolean checkNeonNumber(int inputNumber) { 
        // Calculate square of inputNumber
        int square = inputNumber * inputNumber; 
        // Initialize sumOfSquareDigits 
        int sumOfSquareDigits = 0;
        while(square > 0) {
            sumOfSquareDigits = sumOfSquareDigits + square % 10;
            square = square / 10;
        } 
        /* If sumOfSquareDigits is equal to inputNumber then 
            the number is Neon number, otherwise not */  
        return (sumOfSquareDigits == inputNumber);
    }
}

Output :

Enter any number : 27
27 is NOT a Neon number

Algorithm for Neon Number

1. Calculate the square of the given number(inputNumber).

2. Initialize sumOfSquareDigits variable value to 0. It will represent the sum of digits of the square number.

3. Using while loop
a. Get the rightmost digit of variable square by using (square % 10) and add its value to the variable sumOfSquareDigits.
b. Get rid of the rightmost digit by dividing the square variable with 10. Store the resulting value in  square variable.
c. Continue till square becomes 0.

4. Check whether the variable sumOfSquareDigits is equal to inputNumber.
     a. If both are equal then the inputNumber is a Neon number.
     b. Otherwise, the inputNumber is not a Neon number.

That's all for the day, please mention in comments if you know any other way to implement Neon number program in java.

About The Author

Subham Mittal has worked in Oracle for 3 years .
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