C#

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Threading;

namespace Number_Puzzle_Cs
    public class frmMain : System.Windows.Forms.Form
    {...

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace WindowsApplication5

Public Class2
{
  public void SomeFunction()
  {
    namespace1.Class1 object1 = ...;
    namespace2.Class1 object2 = ...;
  }
}

public Image GetImage(long id)
{
  using (OleDbConnection conn = new OleDbConnection(connectionString))
  {
    using (OleDbCommand cmd = conn.CreateCommand())
    {
      cmd.CommandText = "SELECT image FROM Images WHERE ID = ?";
      cmd.Parameters.Add("ID", OleDbType.Integer).Value = id;
      using (OleDbDataReader reader = cmd.ExecuteReader())
      {
        long length = reader.GetBytes(0, 0, null, 0, 0);
        byte[] buffer = new byte[length];
        length = reader.GetBytes(0, 0, buffer, 0, length);
        if (buffer.Length == length)
        {
         using (MemoryStream ms = new MemoryStream(buffer))
         {
            Image img = Image.FromStream(ms);
            return img;
          }
         }
       }
      }
    }
  }
  return null;
}

public void AddImage(Image img, ImageFormat format)
{
  using (MemoryStream ms = new MemoryStream())
  {
    img.Save(ms, format);
    using (OleDbConnection conn = new OleDbConnection(connectionString))
    {
      using (OleDbCommand cmd = conn.CreateCommand())
      {
        cmd.CommandText = "INSERT INTO Images VALUES(?)";
        cmd.Parameters.Add("image", OleDbType.Binary).Value = ms.GetBuffer();
        cmd.ExecuteNonQuery();
      }
    }
  }
}

Random rnd = new Random(DateTime.Now.Ticks);// Generates different random number sequences.
Random rnd = new Random(1);// Generates always the same random number sequence.
int randomNumber = rnd.Next(1, 21);