Java Program to Check Whether a Number is an Armstrong Number

WAP to check whether a number is an Armstrong number in Java

What is Armstrong Number ?

An Armstrong number (also known as a narcissistic number) is a number that is equal to the sum of the n-th power of its digits, where n is the number of digits.
Example: 153 is an Armstrong number because:
1³+5³+3³=153

Logical Steps:

Take one number.
Initialize a sum variable to 0 and store the original number in a temporary variable.
Use a loop:
- Extract the last digit using no % 10.
- Calculate the cube of the digit and add it to the sum.
- Remove the last digit using no = no / 10.
Repeat the process until the number becomes 0.
Check if the sum is equal to the original number.
- If true, it is an Armstrong number; otherwise, it is not.

Programs:

Below is the simple program:

public class CheckArmstrongNumber
{
    public static void main(String[] args)
    {
        int no = 153;
        int originalNumber = no;
        int sum = 0;

        // Calculate the number of digits
        int temp = no;
        int digits = 0;
        while (temp != 0)
        {
            digits++;
            temp = temp / 10;
        }

        while (no != 0)
        {
            int rem = no % 10;
            int mul = 1;

            // Calculate rem^digits using a basic loop
            for (int i = 0; i < digits; i++)
            {
                mul = mul * rem;
            }

            sum = sum + mul;
            no = no / 10;
        }

        if (sum == originalNumber)
        {
            System.out.println(originalNumber + " is an Armstrong number.");
        }
        else
        {
            System.out.println(originalNumber + " is not an Armstrong number.");
        }
    }
}

Output:

153 is an Armstrong number.

Below is the program by taking user input:

import java.util.Scanner;

public class CheckArmstrongNumber
{
    public static void main(String[] args)
    {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter a number: ");
        int no = scanner.nextInt();

        int originalNumber = no;
        int sum = 0;

        // Calculate the number of digits
        int temp = no;
        int digits = 0;
        while (temp != 0)
        {
            digits++;
            temp = temp / 10;
        }

        while (no != 0)
        {
            int rem = no % 10;
            int mul = 1;

            // Calculate rem^digits using a basic loop
            for (int i = 0; i < digits; i++)
            {
                mul = mul * rem;
            }

            sum = sum + mul;
            no = no / 10;
        }

        if (sum == originalNumber)
        {
            System.out.println(originalNumber + " is an Armstrong number.");
        }
        else
        {
            System.out.println(originalNumber + " is not an Armstrong number.");
        }
    }
}

Output:

Enter a number: 1634
1634 is an Armstrong number.

Program Explanation

Take input from the user using Scanner and store it in an integer variable no.
Example: no = 1634
Initialize a variable sum to 0 to keep track of the sum of the multiplication digits.
int sum = 0;
Calculate the number of digits in the number using a while loop:
- Use a temporary variable temp to avoid modifying the original number.
- Divide the number by 10 in each iteration and increment the digits counter until the number becomes 0.
  Example: For 1634, the number of digits is 4.
Use another while loop that runs until no becomes 0:
- Extract the last digit using no % 10.
  Example: For 1634, the last digit is 4.
- Calculate the power of the digit raised to the number of digits using a for loop
  - Multiply the digit by itself digits times.
    Example: 4⁴=25644=256
- Add the power to the sum:
  Example: sum = 0 + 256 = 256
- Remove the last digit from no by dividing it by 10.
  Example: 1634 becomes 163.
Repeat the process until all digits are processed.
Example:
3⁴=81, 6⁴=1296, 1⁴=1
The sum becomes 256 + 81 + 1296 + 1 = 1634.
Compare sum with the original number (originalNumber)
- If they are equal, the number is an Armstrong number.
- Otherwise, it is not an Armstrong number.
Print the result using System.out.println().
Close the scanner with scanner.close() to avoid resource leaks.

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WAP to check whether a number is an Armstrong number in Java

What is Armstrong Number ?

Logical Steps:

Programs:

Output:

Output:

Program Explanation

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