using System;

using System.Globalization;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        string formula = "0.5 0.5 0.25 + * 0.125 *";

        decimal result = Calculate(formula);

        Console.WriteLine($"{formula} = {result}");

    }

    public static decimal Calculate(string postfixFormula)

    {

        var tokens = postfixFormula.Split(new char[] {' '}, StringSplitOptions.RemoveEmptyEntries);

        var stack = new Stack<decimal>();        

        foreach (var token in tokens)

        {

            switch (token)

            {

                case "*":

                {

                    decimal right = stack.Pop(), left = stack.Pop();

                    stack.Push(left * right);

                    break;

                }

                case "+":

                {

                    decimal right = stack.Pop(), left = stack.Pop();

                    stack.Push(left + right);

                    break;

                }

                default:

                {

                    decimal num = decimal.Parse(token, CultureInfo.InvariantCulture);

                    stack.Push(num);

                    break;

                }

            }

        }

        return stack.Pop();    

    }

}