# Special Number in Java

(Last Updated On: 12/10/2023)

In this blog, we’ll explore the idea of special numbers, look at their definition and examples, talk about how to check for special number in Java, show you an algorithm to identify them and give you a few programs to do it. Let’s set out on this adventure to learn about special numbers and their significance in Java programming.

## What is a Special Number?

In this context, we refer to a number with specific qualities or traits as a “special number.” The specific mathematical relationships, patterns, or significance within a given domain can vary depending on the context, but these properties frequently involve them.

### Special Number Examples

To better grasp the concept of special numbers, let’s explore a few examples:

• Perfect Numbers: Numbers where the sum of their proper divisors equals the number itself, such as 6 (1 + 2 + 3 = 6).
• Armstrong Numbers: Numbers where the sum of their digits raised to the power of the number of digits equals the number itself, like 153 (1^3 + 5^3 + 3^3 = 153).
• Palindromic Numbers: Numbers that read the same forwards and backward, such as 121 or 454.
• These examples highlight the intriguing nature of special numbers and showcase the different characteristics they can possess.

## Steps to Check Special Numbers in Java

To determine if a number is special, we can follow these steps:

1. Take the input number.
2. Perform the necessary calculations or checks based on the specific special number property.
3. If the conditions are satisfied, declare the number as a special number.
4. If the conditions are not met, declare the number as a regular number.

Implementing these steps in Java allows us to identify and differentiate special numbers from other numbers.

### Algorithm

We can use the following algorithm to check for special numbers in Java:

• Accept the input number.
• Use the special number property to perform any necessary calculations or checks.
• Declare the number to be a special number if the requirements are satisfied.
• Declare the amount as a regular number if the prerequisites are not met.
• The output should indicate whether the number is special or not.

## Different Programs to Find Special Numbers in Java

In this section, we will explore various Java programs that demonstrate different methods to find special numbers. These programs will cover a range of special number properties, such as perfect numbers, Armstrong numbers, palindromic numbers, and more. Each program will include the necessary logic and explanations to help you understand the process of identifying special numbers in Java.

### Method 1: Check whether the entered number is a special number or not

```import java.util.Scanner;
public class SpecialNumEx
{
//Array with factorials of 0 to 9
static int factorial[] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880};
public static void main(String args[])
{
Scanner in = new Scanner(System.in);
boolean hasSpecial = false;
//Enter the range values
System.out.print("Enter the lower range: ");
int lower_limit = in.nextInt();
System.out.print("Enter the upper range: ");
int upper_limit = in.nextInt();
//iterates over the given range
for(int i=lower_limit; i<=upper_limit; i++)
{
//use isSpecial() method to check if it is special
if(isSpecialNumber(i))
{
//prints the special number
System.out.print(i+"\t");
hasSpecial = true;
}
}
//executes if the specified range does not have any special number
if(!hasSpecial)
System.out.println("No special numbers found.");
}
//function checks if the number is special or not, if special returns true
private static boolean isSpecialNumber(int n)
{
int digit, sum=0, temp=n;
//Extract digits and sum their factorial
while(temp != 0)
{
//find digits
digit = temp%10;
//finds sum of factorials
sum = sum + factorial[digit];
//removes the last digit from the number
temp = temp/10;
}
//returns true if sum==n, else returns false
return sum == n;
}
}```

Explanation of the code:

This Java program finds and displays all the special numbers that fall within a certain range. A special number is one for which the factorial of its digits added together equals the number itself.

The code prompts the user to enter the lower and upper bounds of the range. The isSpecialNumber() method is then used to iteratively go through each number in the range and determine whether or not it is a special number. The isSpecialNumber() method extracts each digit of the number by using the modulo operator and saves it in the ‘digit’ variable. By utilizing pre-computed factorials from the “factorial” array, we calculate the sum of the factorials of the digits. In each iteration, the ‘temp’ variable subtracts the final digit of the number.

The method returns true, indicating that the number is special, if the factorial sum equals the starting number. Otherwise, false is returned. Any unique numbers that are discovered within the specified range are printed. If no special numbers are found, we display a message stating that no special numbers were discovered. Overall, this code employs a factorial calculation and digit extraction approach to effectively identify and display special numbers within a given range.

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#### Output:

``````Enter the lower range: 1
Enter the upper range: 100
1	2``````

### Method 2: Find special number in particular range

```import java.util.Scanner;
public class SpecialNumEx
{
public static void main(String args[])
{
int num, number, last_digit, sum_Of_Fact = 0;
Scanner sc = new Scanner(System.in);
System.out.print("Enter a number: ");
//reads an integer from the user
number = sc.nextInt();
num = number;
//executes until the condition becomes false
while (number > 0)
{
//finds the alst digit from the given number
last_digit = number % 10;
//variable stores factorial
int fact=1;
//factorial logic
for(int i=1; i<=last_digit; i++)
{
//calculates factorial
fact=fact*i;
}
//calculates the sum of all factorials
sum_Of_Fact = sum_Of_Fact + fact;
//divides the number by 10 and removes the last digit from the number
number = number / 10;
}
//compares the sum with the given number
if(num==sum_Of_Fact)
{
System.out.println(num+ " is a special number.");
}
else
{
System.out.println(num+ " is not a special number.");
}
}
}```

Explanation of the code:
This Java program determines whether or not a given number is a special number. It stores the user’s input as an integer in the “number” variable. The code then performs the following operations:

• It initializes variables like “last digit,” which stores the number’s last digit, “fact,” which computes the factorial, and “sum Of Fact,” which stores the sum of factorials.
• It extracts the last digit of the number using the modulo operator and determines the factorial of that digit using a while loop.
• The variable “sum_Of_Fact” now contains the calculated factorial. To get rid of the last digit, divide the number by 10.
• Following the loop, it compares the factorial sum to the starting value.
• It prints that the number is a special number if they are equal; if not, it prints that it is not a special number.

Overall, this code determines whether a number is special or not by calculating the sum of factorials of its digits and comparing it to the original number.

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#### Output:

``````Enter a number: 1245
1245 is not a special number.``````

### Tips and Tricks for Special Numbers in Java:

Realize the Concept: Understand how special numbers are described and the idea behind them.This will assist you in understanding the reasoning behind how Java recognizes special numbers.

Use the Modulo Operator: To get the last digit of a number, use the modulo operator (%). When dealing with individual numbers, this is a crucial operation.

Implement Factorial Calculation: Special numbers often involve frequent calculations of factorials. To quickly calculate factorials for individual digits, use a factorial calculation method or loop.

Use the Scanner class: Use the Scanner class to allow user input by incorporating it. This gives you the option to interactively determine whether a given number is a special number.

Enhance Loops: To prevent pointless iterations, pay attention to loop conditions and improve them. To extract digits, a common approach involves using a loop that continues until the number becomes zero.

Know the Pronic Number in Java here!

### Real-Life Applicability of Special Number in Java:

Cryptography: Cryptography algorithms can use special numbers to create secure keys or encrypt data.

Mathematics and Number Theory: Special numbers are of interest in number theory because they allow researchers to investigate various mathematical relationships and patterns.

Design of Algorithms: You can use special numbers to create effective algorithms for a variety of computational problems involving numbers.

Game Development: Depending on specific number conditions, special numbers can be used to unlock exclusive features or create custom game codes.

Data Analysis: Special numbers can be used as standards for analyzing data and spotting patterns in a variety of fields, including finance, statistics, and scientific study.

By delving into the real-world applications of special numbers, you can gain a better understanding of their significance and come up with novel ways to use them in your Java programming endeavors.

In our blog on “Special Number in Java”, we have explored the concept of special numbers, examined examples, outlined the steps to check for special numbers, provided an algorithm, and offered different programs to find special numbers in Java. To keep enhancing your coding skills, do check out Newtum’s website and explore our online coding courses covering DJANGO, Core Python, HTML, and more.