Nov 7, 20222 min read

Write a program to print Armstrong Numbers in Java

In this article, we will write a program

To print Armstrong numbers from 0 - 500.
Check whether the given number is Armstrong or not.

Let's start with the definition of the Armstrong numbers.

What is Armstrong's Number?

An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself.

For example,

153 = 1*1*1 + 5*5*5 + 3*3*3 = 153

371 = 3*3*3 + 7*7*7 + 1*1*1 = 371

Code:

1. Print Armstrong Numbers from 0 - 500

class Main {
  public static void main(String[] args) {

    int low = 0, high = 500;
    System.out.print("The Armstrong Numbers from 0 - 500 are: "); 
    for(int number = low + 1; number < high; ++number) {
      int digits = 0;
      int result = 0;
      int originalNumber = number;

      // number of digits calculation
      while (originalNumber != 0) {
        originalNumber /= 10;
        ++digits;
      }

      originalNumber = number;

      // result contains sum of nth power of its digits
      while (originalNumber != 0) {
        int remainder = originalNumber % 10;
        result += Math.pow(remainder, digits);
        originalNumber /= 10;
      }

      if (result == number) {
        System.out.print( number + " ");
      }
    }
  }
}

Output:

2. Check whether the given number is Armstrong or not

import java.util.Scanner;
public class ArmStrong 
{
    public static void main(String[] args) 
    {
        int n, count = 0, a, b, c, sum = 0;
        Scanner s = new Scanner(System.in);
        System.out.print("Enter any integer you want to check:");
        n = s.nextInt();
        a = n;
        c = n;
        while(a > 0)
        {
            a = a / 10;
            count++;
        }
        while(n > 0)
        {
            b = n % 10;
            sum = (int) (sum+Math.pow(b, count));
            n = n / 10;
        }
        if(sum == c)
        {
            System.out.println("Given number is Armstrong");
        }
        else
        {
            System.out.println("Given number is not Armstrong");
        }    
    }
}

Output: