How to name the file name dynamically

static void Main(string[] args)
        {


            const int linesPerFile = 10;
            string path = @"G:\Folder";
            const string destinationFileName = @"G:\Folder\File-Part-{0}.txt";
            //string fileName = "File";
            var maxNumberOfFiles = 10;
            Stopwatch timer = new Stopwatch();



                var fileCounter = 0;

                if (!Directory.Exists(path))
                {
                   DirectoryInfo di = Directory.CreateDirectory(path);
                }

                var destiNationFile = new StreamWriter(string.Format(destinationFileName, fileCounter + 1));
                try
                {

                    // foreach (var bank in BankAcoutNumbers.BANS.Take(100))
                    //{
                    var lineCounter = 0;
                    string line;

                    while (fileCounter <= maxNumberOfFiles)
                    {
                        timer.Start();
                        foreach (var bank in BankAcoutNumbers.BANS.Take(100))
                        {
                            if (lineCounter % linesPerFile == 0)
                            {
                                //lineCounter = 0;
                                destiNationFile.Flush();                                
                                destiNationFile.Dispose();
                                destiNationFile = new StreamWriter(string.Format(destinationFileName, fileCounter + 1));
                                fileCounter++;
                            }

                            destiNationFile.WriteLine(bank);
                            lineCounter++;
                           
                           
                            
                        }

                        fileCounter++;
                        
                        //}


                    }
                    
                        
                    timer.Stop();
                    // Console.WriteLine(BankAcoutNumbers.BANS.Count());
                    Console.WriteLine(timer.Elapsed.Seconds);
                }
                catch (Exception)
                {

                    throw;
                }
            
                      

            // Keep the console window open in debug mode.

            System.Console.WriteLine("Press any key to exit.");
            System.Console.ReadKey();
        } 

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