### Java Program to check if a number is Neon number or not:

In this Java tutorial, we will learn how to check if a number is ‘Neon‘ number or not. A ‘Neon‘ number *is a number whose sum of all digits of square of the number is equal to the number*. For example, ‘9’ is a Neon number. Because, square of 9 is 9*9= 81. Sum of all digits of 81 is 8+1=9. So it is a Neon number. Similarly 1 is also a Neon number. But 8 is not. Algorithm we are going to use is :

### Algorithm to check if a number is Neon or not :

1. Use one while loop. This loop will exit only if user enters -1 as input number. Otherwise, get user input and check if it is ‘Neon’ or not for infinite time.

2. First take the input number from user.

3. Calculate the *square* of the number.

4. Now, find the* sum of all the digits of the square number* using a loop.

5. Finally, check if the sum is equal to the given number or not.

6. If equal, *it is a Neon number*. Else *it is not*.

import java.util.Scanner; public class Main { /** * Utility function for System.out.println * * @param message : string to print */ private static void println(String message) { System.out.println(message); } /** * Method to check if a number is Neon or not * * @param n : Number to check * @return : true if 'n' is a neon number, false otherwise */ private static boolean isNeonNumber(int n) { int square = n * n; int sum = 0; //find the sum of all digits of square while (square > 0) { sum += square % 10; square = square / 10; } //return true if the sum is equal to the input number return (sum == n); } /** * main method * * @throws java.lang.Exception */ public static void main(String[] args) throws java.lang.Exception { Scanner sc = new Scanner(System.in); int no; while (true) { println(""); println("Enter a number to check if it is Neon or not. ( -1 to exit ) : "); no = sc.nextInt(); if (no == -1) { break; } if (isNeonNumber(no)) { println("Input no is Neon."); } else { println("Input no is not Neon."); } } } }

### Sample Output :

Enter a number to check if it is Neon or not. ( -1 to exit ) : 12 Input no is not Neon. Enter a number to check if it is Neon or not. ( -1 to exit ) : 9 Input no is Neon. Enter a number to check if it is Neon or not. ( -1 to exit ) : 90 Input no is not Neon. Enter a number to check if it is Neon or not. ( -1 to exit ) : -1 Process finished with exit code 0