Untitled

using System;

namespace ClassLibrary1
{
    public class Class1
    {
        public static double r; //Rate of interest
        public static double b; //Balance
        public static string i; //Type of interest
        public static double o; //Original Balance
        public static double t = 1; //Time

        public static void Main()
        {
            t = 1;
            BalanceCheck();
            RateOfInterestCheck();
            TypeOfInterestCheck();
            InterestFormula(i);
        }

        public static void BalanceCheck()
        {
            Console.WriteLine("Please enter your balance");
            string tmp = Console.ReadLine();
            if (!double.TryParse(tmp, out b) || b <= 0)
            {
                Console.WriteLine(tmp + " is invalid. Please input a positive number for the balance");
                Main();
            }
            o = b;
        }
        public static void RateOfInterestCheck()
        {
            Console.WriteLine("Please enter the rate of interest ");
            string tmp = Console.ReadLine();
            if (!double.TryParse(tmp, out r) || r <= 0)
            {
                Console.WriteLine(tmp + " is invalid. Please input a positive number for the rate of interest");
                Main();
            }
        }
        public static void TypeOfInterestCheck()
        {
            Console.WriteLine("Please enter the type of interest (simple/compound)");
            i = Console.ReadLine().ToLower();
            if (i != "simple" && i != "s" && i != "compound" && i != "c")
            {
                Console.WriteLine(i + " is not a type of interest. Please enter either \"simple\" or \"compound\"\n");
                Main();
            }
        }

        public static void InterestFormula(string type)
        {
            if (type == "simple" || type == "s")
            {
                b = o + (o * (r / 100) * t);

            }
            else if (type == "compound" || type == "c")
            {
                b = o * Math.Pow(1 + (r / 100), t);
            }
            Console.WriteLine("After " + t + " years, the balance is $" + b);
            CheckIfBalanceIsDoubleOriginal();
        }

        public static void CheckIfBalanceIsDoubleOriginal()
        {
            if (b >= 2 * o)
            {
                Console.WriteLine("It will take " + t + " years for the balance to doubled\n");
                Console.WriteLine("The balance will be " + b);
                Main();
            }
            else
            {
                t++;
                InterestFormula(i);
            }
        }
    }
}