In this tutorial, we will learn how to check whether a given number is Armstrong or not.

What is Armstrong Number ?

Armstrong Number is a number that is equal to the sum of cubes of its digits. For example, 153 is an Armstrong number since 1³ + 5³ + 3³ = 153.

Algorithm

1Input :  number n
2Step 1:  Start
3Step 2:  Read number n
4Step 3:  Initialize variable sum to 0 and temp to n
5Step 4:  If temp not equal to 0 Go to Step 5 , else Go to Step 9 
6Step 5:  digit = temp % 10 
7Step 6:  temp = temp / 10 
8Step 7:  sum = sum + digit * digit * digit
9Step 8:  Repeat Step 4 
10Step 9:  If sum is equal to n Print "Armstrong"
11Step 10: Else Print "Not Armstrong"
12Step 11: Stop
13Output: Armstrong Number / not an Armstrong Number

Code Implementation

1import java.util.Scanner;
2
3public class ArmstrongNumber {
4
5  public static void main(String[] args) {
6    Scanner sc = new Scanner(System.in);
7    System.out.println("Enter Number : ");
8    int n = sc.nextInt();
9    int temp = n;
10    int sum = 0;
11
12    while(temp !=0) {
13      int digit = temp % 10;
14      temp = temp / 10;
15      sum = sum + digit * digit * digit ;
16    }
17
18    if (sum == n) {
19      System.out.printf("%d is an Armstrong Number \n", n);
20    }else {
21      System.out.printf("%d is Not an Armstrong Number \n", n);
22    }
23  }
24}

Output 1:

1Enter Number : 153
2153 is an Armstrong Number

Output 2:

1Enter Number : 321
2321 is not an Armstrong Number