Please try : publicstaticvoidMain(string[]args) { tampil(10); } privatestaticvoidtampil(inti) { Console.WriteLine("Halo"+i.ToString()); if(i>0) tampil(i-1); }

Eight hours residence time may make it very difficult to make it a continuous reaction. Elevated temperatures are needed for Naphthalene sulfonation. Use of sulfuric acid adds to the problem....