Finding out a Kaprekar number in Java

By Kollabathula Preetham

Hey guys! The topic for today is finding out if a number is a Kaprekar number or not in Java.
So what is a Kaprekar number?

Kaprekar Number in Java

When you square a number, then split the number into two integers, sum those two integers and you end up with the same value you started with, then such a number is called as Kaprekar number.

Explanation

Example 1:
Consider a positive whole number: 45
Square the number: 45 x 45 = 2025
Split the squared number into two halves.
(i.e) 20 and 25.
Add these two halves and if we get the number we started with, then it is a Kaprekar number.
20 + 25 = 45.
Hence 45 is a Kaprekar number.

Example 2:
Consider a positive whole number: 4
Square the number: 4 x 4 = 16
Split the squared number into two halves.
(i.e) 1 and 6.
Add these two halves and if we get the number we started with, then it is a Kaprekar number.
1 + 6 = 7.
Hence 7 is a Not a Kaprekar number.

Code for finding out if a number is Kaprekar number or not in Java

import java.util.*;
class Kaprekar{
    public static void main(String[]args)
    {
        Scanner scan = new Scanner(System.in);
        System.out.print("Enter the number: ");
        int number = scan.nextInt();
        int square = number * number; // can use long for bigger numbers
        String squaredStr = Integer.toString(square); 
        String left = "0";
        String right = "0";
        for(int i = 0; i < squaredStr.length() / 2; i++)
        {
            left = left + squaredStr.charAt(i); //storing the first half of string
        }
        for(int i = squaredStr.length() / 2; i < squaredStr.length(); i++)
        {
            right = right + squaredStr.charAt(i); //storing second half of string
        }
        int n1 = Integer.parseInt(left);
        int n2 = Integer.parseInt(right);
        if(n1 + n2 == number)
        {
            System.out.println(number + " is a Kaprekar Number!");
        }
        else
        {
            System.out.println(number + " is not a Kaprekar Number.");
        }
    }
}

Output:

Hope you understand the code 🙂
Any questions please feel free to drop in your comments.

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