using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string pattern = @"(\d+|)[^\d]*(\d+)[^\d]+(\d+\.\d+)";

        string input = @"27x1.5";

        //"5x(3x1.5)"; "421x(332x1.0)";

        foreach (Match m in Regex.Matches(input, pattern))

        {

            Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);

            Console.WriteLine("\n");

            for (var index = 0; index < m.Groups.Count; index++)

            {

                Console.WriteLine("'{0}' found at index {1}.", m.Groups[index], index);

            }

        }

    }

}