using System;

public class Program

{

    public static void Main()

    {

        DateTime entrada = new DateTime(2017, 9, 18).AddHours(11);

        DateTime salida = new DateTime(2017, 9, 26).AddHours(9);

        Console.WriteLine("entrada: " + entrada);

        Console.WriteLine("salida: " + salida);

        TimeSpan timespan = salida - entrada;

        Console.WriteLine("timespan: " + timespan);

        double totalDays = timespan.TotalDays;

        Console.WriteLine("TotalDays: " + totalDays);

        Console.WriteLine("TotalDays ROUND: " + Math.Round(totalDays)); // Math.Round(totalDays) Esto es lo que se inserta en la base 

    }

}