Java Program to Check Magic Number

Posted in Java Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 100 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the world of programming, the concept of magic numbers is a fascinating one.

A magic number is a number in which the eventual sum of its digits, when the sum is recursively calculated, leads to a single-digit number that is 1. If the final sum is not 1, the number is not considered magic.

In this tutorial, we'll explore a Java program that checks whether a given number is a magic number or not.

📄 Example

Let's dive into the Java code that checks for the magic number property.

MagicNumberChecker.java

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public class MagicNumberChecker {

// Function to check if a number is magic
static boolean isMagicNumber(int num) {
  while (num > 9) {
    int sum = 0;

    // Calculate the sum of digits
    while (num > 0) {
      sum += num % 10;
      num /= 10;
    }

    num = sum;
  }

  // Check if the final sum is 1
  return (num == 1);
}

// Driver program
public static void main(String[] args) {
  // Replace this value with your desired number
  int number = 19;

  // Check if the number is magic
  if (isMagicNumber(number)) {
    System.out.println(number + " is a Magic Number.");
  } else {
    System.out.println(number + " is not a Magic Number.");
  }
}
}

💻 Testing the Program

To test the program with different numbers, simply replace the value of number in the main method.

Output

19 is a Magic Number.

Compile and run the program to see whether the number is a magic number or not.

🧠 How the Program Works

The program defines a class MagicNumberChecker containing a static method isMagicNumber that takes an integer as input and checks if it is a magic number.
Inside the method, it iteratively calculates the sum of the digits of the number until the number becomes a single-digit number.
It then checks if the final sum is equal to 1, indicating a magic number.

📏 Between the Given Range

Let's take a look at the java code that checks for Magic Numbers within the specified range.

MagicNumberChecker.java

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public class MagicNumberChecker {

  // Function to check if a number is magic
  static boolean isMagic(int num) {
    while (num > 9) {
      int sum = 0;
      while (num > 0) {
        sum += num % 10;
        num /= 10;
      }
      num = sum;
    }
    return num == 1;
  }

  // Driver program
  public static void main(String[] args) {
    System.out.println("Magic Numbers in the range 1 to 50: ");
    for (int i = 1; i <= 50; i++) {
      if (isMagic(i)) {
        System.out.print(i + " ");
      }
    }
  }
}

💻 Testing the Program

Output

Magic Numbers in the range 1 to 50:
1 10 19 28 37 46

Simply compile and run the program to see the magic numbers.

🧠 How the Program Works

The program defines a class MagicNumberChecker containing a static method isMagic to check if a given number is a magic number.
The isMagic method iteratively sums the digits of the number until it becomes a single-digit number.
The main method tests and prints the magic numbers within the specified range.

🧐 Understanding the Concept of Magic Numbers

A magic number is a number in which the sum of its digits leads to a single-digit number, and that single-digit number is 1.

For example, the number 19 is a magic number because the sum of its digits (1 + 9) is 10, and the sum of 1 and 0 is 1.

🎢 Optimizing the Program

While the provided program is effective, consider exploring and implementing optimizations or additional features based on your specific requirements.

Feel free to incorporate and modify this code as needed for your specific use case. Happy coding!