public static void Main()
Console.WriteLine("would you like to go from hex to denary(HD) or denary to hex(DH)");
string Decision = Console.ReadLine();
Console.WriteLine("Please enter BinaryValue");
string binaryNum = Console.ReadLine();
string [] arrayNum = new string [binaryNum.Length];
for(i = 0; i < binaryNum.Length; i++)
arrayNum[i] = binaryNum.Substring(i, 1);
for(i = 0; i < binaryNum.Length; i++)
string x = arrayNum[i-3] + arrayNum[i-2] + arrayNum[i-1] + arrayNum[i];