I have used Visual Studio 2012 for debugging purpose. But you can use any version of visul studio as per your availability..

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
public class csharpExercise
{
    static void Main(string[] args)
    {
 
        int i, num, sum = 0;
 
        // Reading number
        Console.Write("Enter any number: ");
        num = Convert.ToInt32(Console.ReadLine());
 
        for (i = 1; i <= num; i += 2)
        {
            //Adding current odd number to sum variable
            sum += i;
        }
        Console.WriteLine("Sum of all odd numbers between 1 to " + num + " = " + sum);
 
        Console.ReadLine();
    }
}

Result:

Enter any number: 15

Sum of all odd numbers between 1 to 15 = 64