using System;

public class Program

{

    public static double CalculateMonthlyRepayment(double initialRate, decimal borrowingAmount, int? remainingTerm)

    {

        var monthlyRate = Convert.ToDecimal(initialRate / 100 / 12);

        var result = 0.0;

        Console.WriteLine(initialRate);

        Console.WriteLine(monthlyRate);

        if(initialRate == 0){

            result = Convert.ToDouble(borrowingAmount / remainingTerm);

        }else{

            result = Convert.ToDouble(borrowingAmount * monthlyRate) / (1 - Math.Pow(1 + Convert.ToDouble(monthlyRate), -1 * remainingTerm.GetValueOrDefault()));

        }

        return Convert.ToDouble(Math.Round(result, 2, MidpointRounding.ToEven));

    }

​

    public static decimal CalculateTotalPayment(int dealPeriod, double monthlyRepayment)

    {

        return Convert.ToDecimal(Math.Round(dealPeriod * 12 * monthlyRepayment, 2));

    }

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Console.WriteLine(CalculateMonthlyRepayment(0, 100000, 300)); // 300 months

        Console.WriteLine("------");

        Console.WriteLine(CalculateMonthlyRepayment(0.0, 100000, 300)); // 300 months

        Console.WriteLine("------");

        Console.WriteLine(CalculateMonthlyRepayment(1, 100000, 300)); // 300 months

    }

}