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## to Armstrong Numbers in the C# Track

Published at Apr 17 2019 · 0 comments
Instructions
Test suite
Solution

#### Note:

This exercise has changed since this solution was written.

An Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits.

For example:

• 9 is an Armstrong number, because `9 = 9^1 = 9`
• 10 is not an Armstrong number, because `10 != 1^2 + 0^2 = 1`
• 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
• 154 is not an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`

Write some code to determine whether a number is an Armstrong number.

## Running the tests

To run the tests, run the command `dotnet test` from within the exercise directory.

Initially, only the first test will be enabled. This is to encourage you to solve the exercise one step at a time. Once you get the first test passing, remove the `Skip` property from the next test and work on getting that test passing. Once none of the tests are skipped and they are all passing, you can submit your solution using `exercism submit ArmstrongNumbers.cs`

## Further information

For more detailed information about the C# track, including how to get help if you're having trouble, please visit the exercism.io C# language page.

## Source

### ArmstrongNumbersTest.cs

``````// This file was auto-generated based on version 1.0.0 of the canonical data.

using Xunit;

public class ArmstrongNumbersTest
{
[Fact]
public void Single_digit_numbers_are_armstrong_numbers()
{
Assert.True(ArmstrongNumbers.IsArmstrongNumber(5));
}

[Fact(Skip = "Remove to run test")]
public void There_are_no_2_digit_armstrong_numbers()
{
Assert.False(ArmstrongNumbers.IsArmstrongNumber(10));
}

[Fact(Skip = "Remove to run test")]
public void Three_digit_number_that_is_an_armstrong_number()
{
Assert.True(ArmstrongNumbers.IsArmstrongNumber(153));
}

[Fact(Skip = "Remove to run test")]
public void Three_digit_number_that_is_not_an_armstrong_number()
{
Assert.False(ArmstrongNumbers.IsArmstrongNumber(100));
}

[Fact(Skip = "Remove to run test")]
public void Four_digit_number_that_is_an_armstrong_number()
{
Assert.True(ArmstrongNumbers.IsArmstrongNumber(9474));
}

[Fact(Skip = "Remove to run test")]
public void Four_digit_number_that_is_not_an_armstrong_number()
{
Assert.False(ArmstrongNumbers.IsArmstrongNumber(9475));
}

[Fact(Skip = "Remove to run test")]
public void Seven_digit_number_that_is_an_armstrong_number()
{
Assert.True(ArmstrongNumbers.IsArmstrongNumber(9926315));
}

[Fact(Skip = "Remove to run test")]
public void Seven_digit_number_that_is_not_an_armstrong_number()
{
Assert.False(ArmstrongNumbers.IsArmstrongNumber(9926314));
}
}``````
``````﻿using System;

public static class ArmstrongNumbers
{
public static bool IsArmstrongNumber(int number)
{
int sum = 0;
Char[] numbers = number.ToString().ToCharArray();

foreach(char c in numbers)
{
Char.GetNumericValue(c);
sum += (int)(Math.Pow(Char.GetNumericValue(c), numbers.Length));
}

return sum == number;
}
}``````

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