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An Armstrong number or a plus perfect number) in a given number base is a number that is the sum of its own digits each raised to the power of the number of digits.
An Armstrong number is a number that is equal to the sum of cubes of its digits.
Examples of these are 0, 1, 153, 370, 371 and 407
Lets look at 153 as an example
(1 * 1 * 1) = 1
(5 * 5 * 5) = 125
(3 * 3 * 3) = 27
Now add 1 + 125 + 27 = 153
Example
using System;
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
int myNumber, r, sumNumber = 0, tempNumber;
Console.Write("Enter the Number= ");
myNumber = int.Parse(Console.ReadLine());
tempNumber = myNumber;
while (myNumber > 0)
{
r = myNumber % 10;
sumNumber = sumNumber + (r * r * r);
myNumber = myNumber / 10;
}
if (tempNumber == sumNumber)
Console.Write("An Armstrong Number.");
else
Console.Write("Not an Armstrong Number.");
Console.ReadLine();
}
}
}
Test runs of this are
Enter the Number= 153 An Armstrong Number. Enter the Number= 154 Not an Armstrong Number.