PerfectNumbers

PerfectionTest.cs

using NUnit.Framework;

namespace Tests
{
	public class PerfectionTest
	{
		[SetUp]
		public void Setup()
		{
		}

		[Test]
		public void PerfectNumberTest()
		{
			Assert.IsTrue(ObssConsoleApp.PerfectNumber.IsPerfectNumber(6));
			Assert.IsTrue(ObssConsoleApp.PerfectNumber.IsPerfectNumber(28));
			Assert.IsTrue(ObssConsoleApp.PerfectNumber.IsPerfectNumber(496));
			
			Assert.IsFalse(ObssConsoleApp.PerfectNumber.IsPerfectNumber(10));
		}
	}
}

PerfectNumber.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;

namespace ObssConsoleApp
{
	public static class PerfectNumber
	{
		#region Methods

		public static bool IsPerfectNumber(int number)
		{
			var multipliers = FindMultipliers(number);
			if (multipliers == null || !multipliers.Any())
			{
				return false;
			}

			return multipliers.Sum() == number;
		}

		public static IEnumerable<int> FindMultipliers(int number)
		{
			if (PrimeNumbers.IsPrime(number))
			{
				return new[] { number };
			}
			
			List<int> result = new List<int>();
			
			for (int i = 2; i < number / 2; i++)
			{
				if (number % i == 0)
				{
					result.Add(i);
				}
			}

			if (result.Any() && !result.Contains(1))
			{
				result.Add(1);
			}

			return result;
		}

		#endregion
	}
}

PrimeNumbers.cs

using System;

namespace ObssConsoleApp
{
	public static class PrimeNumbers
	{
		public static bool IsPrime(int number)
		{
			if (number < 0)
			{
				throw new Exception("Number can not be negative!");	
			}

			if (number == 0 || number == 1)
			{
				return false;
			}
			
			if (number == 2)
			{
				return true;	
			}
			
			for (int i = 2; i < number; i++)
			{
				if (number % i == 0)
				{
					return false;
				}
			}

			return true;
		}
	}
}

PrimeNumberTest.cs

using NUnit.Framework;

namespace Tests
{
	public class Tests
	{
		[SetUp]
		public void Setup()
		{
		}

		[Test]
		public void PrimeNumberTest()
		{
			Assert.IsTrue(ObssConsoleApp.PrimeNumbers.IsPrime(2));
			Assert.IsTrue(ObssConsoleApp.PrimeNumbers.IsPrime(3));
			Assert.IsTrue(ObssConsoleApp.PrimeNumbers.IsPrime(5));
			Assert.IsTrue(ObssConsoleApp.PrimeNumbers.IsPrime(7));
			Assert.IsTrue(ObssConsoleApp.PrimeNumbers.IsPrime(11));
			Assert.IsTrue(ObssConsoleApp.PrimeNumbers.IsPrime(13));
			
			Assert.IsFalse(ObssConsoleApp.PrimeNumbers.IsPrime(4));
			Assert.IsFalse(ObssConsoleApp.PrimeNumbers.IsPrime(10));
			Assert.IsFalse(ObssConsoleApp.PrimeNumbers.IsPrime(15));
			Assert.IsFalse(ObssConsoleApp.PrimeNumbers.IsPrime(25));
			Assert.IsFalse(ObssConsoleApp.PrimeNumbers.IsPrime(27));
			Assert.IsFalse(ObssConsoleApp.PrimeNumbers.IsPrime(30));
		}
	}
}