IsEven.cs

public interface IEven
{
};

public interface IOdd
{
};

public abstract class EvenOrOddNumber
{

	protected int _value;

	public static EvenOrOddNumber CreateInstanceEvenOrOddNumber(int x)
	{
		EvenOrOddNumber newCreation;

		switch (x)
		{
			case 1:
				newCreation = new One();
				break;

			case 2:
				newCreation = new Two();
				break;

			default:
				throw new System.ArgumentException("Number not supported");
		}

		if (newCreation is IEven && newCreation is IOdd)
		{
			throw new System.ArgumentException("Number cannot be even and odd");
		}

		return newCreation;

	}

	public int Value
	{
		get
		{
			return _value;
		}
	}

	public bool isEven()
	{
		bool result;

		if (this is IEven)
		{
			result = true;
		}
		else
		{
			result = false;
		}

		return result;
	}

	public bool isOdd()
	{
		bool result;

		if (this is IOdd)
		{
			result = true;
		}
		else
		{
			result = false;
		}

		return result;
	}
};

public class One : EvenOrOddNumber, IOdd
{

	public One()
	{
		_value = 1;
	}

};

public class Two : EvenOrOddNumber, IEven
{

	public Two()
	{
		_value = 2;
	}

};

class Program
{
	static void Main(string[] args)
	{
		EvenOrOddNumber number = EvenOrOddNumber.CreateInstanceEvenOrOddNumber(1);
		EvenOrOddNumber number2 = EvenOrOddNumber.CreateInstanceEvenOrOddNumber(2);

		Console.WriteLine("is {0} even? {1} and is {2} even? {3}", number.Value, number.isEven().ToString(), number2.Value, number2.isEven().ToString());
		Console.ReadLine();
	}
}