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 :
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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.
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First take the input number from user.
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Calculate the square of the number.
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Now, find the_ sum of all the digits of the square number_ using a loop.
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Finally, check if the sum is equal to the given number or not.
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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