using System;
using System.IO;
class SlicingFile
{
    static void Main()
    {
        Slice("hubble.jpg", @"\..", 10);
    }
    static void Slice(string sourceFile, string destinationDirectory, int parts)
    {
        byte[] buffer = new byte[4096];
        int indexRead = 0;
        long fileSize = new FileInfo(sourceFile).Length;
        string extension = new FileInfo(sourceFile).Extension;
        int pieceSize = (int)Math.Ceiling((decimal)fileSize / parts);
        using (FileStream reader = new FileStream(sourceFile, FileMode.Open))
        {
            string destinationFileName = "Part-1" + extension;
            using (FileStream writer = new FileStream(destinationFileName, FileMode.Append))
            {
                for (int part = 0; part < parts; part++)
                {
                    int indexWrite = 0;
                    long currentPieceSize = 0;
                    while (currentPieceSize < pieceSize)
                    {
                        // read piece
                        int bytesRead = reader.Read(buffer, indexRead, buffer.Length);
                        if (bytesRead == 0) break;
                        // write piece
                        writer.Write(buffer, indexWrite, bytesRead);
                        indexRead += bytesRead;
                        indexWrite += bytesRead;
                        currentPieceSize += bytesRead;
                    }
                    destinationFileName = string.Format("Part-{0}", part + 2) + extension;
                }
            }
        }
    }
}