Java Program for Strong Number

If sum of the factorial of each digit is equal to the given number then it is is called as Strong Number. In this article, we will show you, How to write a Java Program for Strong Number using While Loop, For Loop, and Functions. We will also show you, How to print Strong Numbers between 1 to n.

Java Program for Strong Number using While Loop

This program allows the user to enter any integer value. Next, it will check whether the given number is a strong number or not using While Loop.

// Java program for Strong Number
import java.util.Scanner;

public class StrongNumber1 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Number, Temp, Reminder, Sum = 0, i, Factorial;
		sc = new Scanner(System.in);
		
		System.out.print(" Please Enter any Number : ");
		Number = sc.nextInt();		
		
		Temp = Number;
		while( Temp > 0)
		{
			Factorial = 1; 
			i = 1; 
		    Reminder = Temp % 10;
		    while (i <= Reminder)
		    {
		     	Factorial = Factorial * i;
		     	i++;
		    }
		    System.out.println(" The Factorial of " + Reminder + "  =  " + Factorial);
		     Sum = Sum + Factorial;
		     Temp = Temp /10;
		}
		
		System.out.println(" The Sum of the Factorials of a Given Number " + Number + " =  " + Sum);
		
		if ( Number == Sum )
		{
			System.out.println("\n " + Number + " is a Strong Number");
		}
		else
		{
		   System.out.println("\n " + Number + " is Not a Strong Number");
		}
	}
}

OUTPUT

ANALYSIS

User Entered value: Number = 145 and Sum = 0
Temp = Number = 145

First Iteration: while( Temp > 0)
Reminder = Temp % 10 => 145 % 10
Reminder = 5

Next, it will enter into Inner While loop. Here it will calculate the factorial of 5 = 120. Please refer Factorial Program in Java article

Sum = Sum +120 => 0 + 120
Sum = 120

Temp = Temp /10 => 145 /10
Temp = 14

Second Iteration: while( 14 > 0)
From the first Iteration the values of both Temp and Sum has changed: Temp = 14 and Sum = 120
Reminder = 14 % 10 = 4

Next, it will calculate the factorial of 4, and that is 24.
Sum = 120 + 24
Sum = 144

Temp = 14 /10
Temp = 1

Third Iteration: while( 1 > 0)
From the Second Iteration: Temp = 1 and Sum = 144
Reminder = 1 % 10 = 0

Next, the factorial of 1 is 1
Sum = 144 + 1
Sum = 145

Temp = 1 / 10
Temp = 0

Here Temp = 0 so, the condition inside the while loop will fail

if ( Number == Sum ) => if(145 = 145) – Condition is True. So, given number is a Strong Number

Java Program for Strong Number using For Loop

This program allows the user to enter any integer value. Next, it will check whether the given number is strong number or not using For Loop.

// Java program for Strong Number
import java.util.Scanner;

public class StrongNumber2 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Number, Temp, Reminder, Sum = 0, i, Factorial;
		sc = new Scanner(System.in);
		
		System.out.print(" Please Enter any Number : ");
		Number = sc.nextInt();		
		
		for(Temp = Number; Temp > 0; Temp = Temp /10)
		{
			Factorial = 1; 
			
		    Reminder = Temp % 10;
		    for(i = 1; i <= Reminder; i++)
		    {
		     	Factorial = Factorial * i;
		    }
		    System.out.println(" The Factorial of " + Reminder + "  =  " + Factorial);
		     Sum = Sum + Factorial;
		}
		
		System.out.println(" The Sum of the Factorials of a Given Number " + Number + " =  " + Sum);
		
		if ( Number == Sum )
		{
			System.out.println("\n " + Number + " is a Strong Number");
		}
		else
		{
		   System.out.println("\n " + Number + " is Not a Strong Number");
		}
	}
}

OUTPUT

We just replaced the While loop in the above example with the For loop. If you don’t understand the For Loop, please refer: FOR LOOP

Java Program for Strong Number using Method

This program is same as first example but we separated the logic and placed it in the separate method.

// Java program for Strong Number
import java.util.Scanner;

public class StrongNumber3 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Number, Temp, Reminder, Sum = 0, Factorial;
		sc = new Scanner(System.in);
		
		System.out.print(" Please Enter any Number : ");
		Number = sc.nextInt();		
		
		for(Temp = Number; Temp > 0; Temp = Temp /10)
		{
			Factorial = 1; 		
		    Reminder = Temp % 10;
		    
		    // Calling Calculate_factorial Function
		    Factorial = Factorial(Reminder);
		    
		    System.out.println(" The Factorial of " + Reminder + "  =  " + Factorial);
		    Sum = Sum + Factorial;
		}
		
		System.out.println(" The Sum of the Factorials of a Given Number " + Number + " =  " + Sum);
		
		if ( Number == Sum )
		{
			System.out.println("\n " + Number + " is a Strong Number");
		}
		else
		{
		   System.out.println("\n " + Number + " is Not a Strong Number");
		}
	}
	public static int Factorial(int num)
	{
		if (num == 0 || num == 1)
			return 1;
		else
		    return num * Factorial (num -1);
	}
}

OUTPUT

Java Program to Print Strong Numbers from 1 to N

This program will accept the Minimum and maximum values from user. Next, it will print list of strong numbers between minimum and maximum value.

import java.util.Scanner;

public class PrintStrongNumbers1 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Number, minimum, maximum, Temp, Sum = 0;
		sc = new Scanner(System.in);
		
		System.out.print(" Please Enter the Minimum value : ");
		minimum = sc.nextInt();			
		
		System.out.print(" Please Enter the Maximum value : ");
		maximum = sc.nextInt();	
		
		for(Number = minimum; Number <= maximum; Number++)
		{
			Temp = Number; 
			Sum = StrongNumber(Temp);
		
			if (Number == Sum )
			{
				System.out.println(" " + Number + " is a Strong Number");
			}
		}
	}
	public static int Factorial(int num)
	{
		if (num == 0 || num == 1)
			return 1;
		else
		    return num * Factorial (num -1);
	}
	public static int StrongNumber(int num)
	{
		int Temp, Reminder, Sum = 0, Factorial;
		
		for(Temp = num; Temp > 0; Temp = Temp /10)
		{
			Factorial = 1; 			
			Reminder = Temp % 10;
			Factorial = Factorial(Reminder);
			Sum = Sum + Factorial;
		}
		return Sum;
	}
}

OUTPUT

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