using System;

    using System.Linq;              

public class Program

{

    public static void Main()

    {

        int[] number = {1, 1, 2, 2, 3, 4};

​

        var result = number

           .GroupBy(x => x) // group your numbers

           .Select(x => new {x.Key, Count = x.Count()}) // project 

           .GroupBy(x => x.Count) // group the count

           .OrderByDescending(x => x.Key) // order by count

           .FirstOrDefault(); // pick the highest group

​

        foreach (var item in result)

           Console.WriteLine(item);

​

    }

}