C# When to explicity implement an interface

You will explicitly implement interface mainly for these reasons

1>If two of the implemented interfaces have the same method signature.Then implementing them explicitly is the only way.

using System;

namespace ConsoleApplication5

{

    class Program

    {

        static void Main(string[] args)

        {

            var calc = new Calculator();

            /*Note: When you implement an interface explicitly,

            then casting your class instance into that interface,

             is the only way to access it's methods*/

            ((IOrderCount)calc).GetCount();    //Displays Order Count

            ((IInventoryCount)calc).GetCount();//Displays Inventory Count

        }

    }

    interface IOrderCount

    {

         void GetCount();

    }

    interface IInventoryCount

    {

        void GetCount();

    }

    public class Calculator  : IOrderCount, IInventoryCount

    {

          void IOrderCount.GetCount()

        {

            Console.WriteLine("Order Count");

        }

        void IInventoryCount.GetCount()

        {

            Console.WriteLine("Inventory Count");

        }

    }

}

2>Another reason you want to explicitly implement an interface is if you want to focus only on that interface when using it. For instance in the example above, when I do  ((IOrderCount)calc)  I can only access methods on IOrdercount.