using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var regexp = new Regex(@"[^\d&\.]");

        var valor = "4.5+8-8d5+5.4";

        var arrNumeros = regexp.Split(valor);

        Console.WriteLine(arrNumeros[0]);

        Console.WriteLine(arrNumeros[1]);

        Console.WriteLine(arrNumeros[2]);

        Console.WriteLine(arrNumeros[3]);

        Console.WriteLine(arrNumeros[4]);

    }

}