I tried to make a multicalculator which could hold a lot of features like cos ton and conversions but I have been stuck with the following errors on the image for quite some time can someone please help? I am not sure what is causing the problem and I haven't learned how to use the debugging functionality yet.
The full code:
using System;
namespace Calculator
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Enter the first number:");
            double num1 = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("Enter the second number (if applicable):");
            double num2 = Convert.ToDouble(console.ReadLine());
            Console.WriteLine("Enter the operation (A, S, -, +, M, /, C, T, H, L, LOG, IN, DEG, SYN, COT, CC, VC, LC, HC, DC, OC, BC):");
            string op = Console.ReadLine();
            Calculator calc = new Calculator(num1, num2);
            double result = calc.Calculate(op);
            Console.WriteLine("Result: " + result);
        }
    }
    class Calculator
    {
        private double num1;
        private double num2;
        public Calculator(double num1, double num2)
        {
            this.num1 = num1;
            this.num2 = num2;
        }
        public double Calculate(string op)
        {
            switch (op)
            {
                case "A":
                    return Math.Abs(num1);
                case "S":
                    return Math.Sqrt(num1);
                case "-":
                    return num1 - num2;
                case "+":
                    return num1 + num2;
                case "M":
                    return num1 * num2;
                case "/":
                    return num1 / num2;
                case "C":
                    return Math.Cos(num1);
                case "T":
                    return Math.Tan(num1);
                case "H":
                    return Hypotenuse(num1, num2);
                case "L":
                    return Math.Log(num1);
                case "LOG":
                    return Math.Log10(num1);
                case "IN":
                    return Math.Log(num1, num2);
                case "DEG":
                    return Math.ToDegrees(num1);
                case "SYN":
                    return Math.Sin(num1);
                case "COT":
                    return 1 / Math.Tan(num1);
                case "CC":
                    return CurrencyConverter(num1, num2);
                case "VC":
                    return VolumeConverter(num1, num2);
                case "LC":
                    return LengthConverter(num1, num2);
                case "HC":
                    return HexConverter(num1);
                case "DC":
                    return DecimalConverter(num1);
                case "OC":
                    return OctalConverter(num1);
                    break;
            }
        }
    }
}