Krishnamurthy Number Java

Krishnamurthy number is another special number in Java. A number is said to be Krishnamurthy if the factorial sum of all its digits is equal to that number. Krishnamurthy number is also referred to as a Strong number. Just like Prime and Armstrong numbers, Krishnamurthy number is also frequently asked by the interviewers but with it's another name, i.e., Strong number.

These are the following steps which we use to check Krishnamurthy number

We first take a number.
We then find the factorial of each digit of the number.
We add the factorial of each digit and store it into another variable.
If the sum of the factorial of each digit is the same as the original number, the number is a Krishnamurthy number.

Let's take an example of Krishnamurthy number.

Number = 145
= 1! + 4! + 5!
= 1 + ( 4 * 3 * 2 * 1 ) + ( 5 * 4 * 3 * 2 * 1 )
= 1 + 24 + 120
= 145

Let's implement a program to check whether the user entered number is a Krishnamurthy number or not.

KrishnamurthyNumber.java

//import required classes and packages
import Java.util.*; 
import java.io.*; 
import java.util.Scanner;

//create KrishnamurthyNumber class to check whether the given number is a Krishnamurthy number or not
class KrishnamurthyNumber { 
	
	// create fact() method to calculate the factorial of the number 
	static int fact(int number) 
	{ 
		int f = 1; 
		while (number != 0) { 
			f = f * number; 
			number--; 
		} 
		return f; 
	} 

	// create checkNumber() method that returns true when it founds number krishnamurthy 
	static boolean checkNumber(int number) 
	{ 
		int sum = 0;	//initialize sum to 0 
		
		int tempNumber = number;	//create a copy of the original number 
		
		//perform operation until tempNumber will not equal to 0
		while (tempNumber != 0) { 
			// calculate the factorial of the last digit of the tempNumber and then add it to the sum
			sum = sum + fact(tempNumber % 10); 

			// replace the value of tempNumber by tempNumber/10 
			tempNumber = tempNumber / 10; 
		} 

		// Check whether the number is equal to the sum or not. If both are equal, number is krishnamurthy number
		if(sum == number)
			return true;
		else
			return false;
	} 

	// main() method start
	public static void main(String[] args) 
	{ 
		int n;	//initialize variable n
		
		//create scanner class object to read data from user
		Scanner sc = new Scanner(System.in);
		
		//custom message
		System.out.println("Enter any number:");
		
		//store user entered value into variable n
		n = sc.nextInt();
	   
		if (checkNumber(n)) 
			System.out.println(n + " is a krishnamurthy number"); 
		else
			System.out.println(n + "is not a krishnamurthy number"); 
	} 
}

Output

Let's implement one more program to get all the Krishnamurthy number in a given range

FindAllKrishnamurthyNumber.java

//import required classes and packages
import java.util.*; 
import java.io.*; 
import java.util.Scanner;

//create FindAllKrishnamurthyNumber class to get all the Krishnamurthy number in a given range
class FindAllKrishnamurthyNumber
{
	//main() method start
	public static void main(String args[])
	{
		int range;
		
		//create scanner class object
		Scanner sc=new Scanner(System.in);
		
		//show custom message
		System.out.println("Enter the value of range");
		
		//store user entered value into variable range
		range = sc.nextInt();

		for(int i = 1; i <= range; i++)
			checkNumber(i);
	}

	// create fact() method to calculate the factorial of the number 
	static int fact(int number) 
	{ 
		int f = 1; 
		while (number != 0) { 
			f = f * number; 
			number--; 
		} 
		return f; 
	} 

	// create checkNumber() method to check krishnamurthy number
	static void checkNumber(int number) 
	{ 
		int sum = 0;	//initialize sum to 0 
		
		int tempNumber = number;	//create a copy of the original number 
		
		//perform operation until tempNumber will not equal to 0
		while (tempNumber != 0) { 
			// calculate the factorial of the last digit of the tempNumber and then add it to the sum
			sum = sum + fact(tempNumber % 10); 

			// replace the value of tempNumber by tempNumber/10 
			tempNumber = tempNumber / 10; 
		} 

		// Check whether the number is equal to the sum or not. If both are equal, the number is Krishnamurthy number
		if(sum == number)
			System.out.println(number + " is a krishnamurthy number"); 
	}
}

Output