public void WorksheetPasteDate()
{
MemoryStream stream = SpreadsheetReader.Create();
SpreadsheetDocument doc = SpreadsheetDocument.Open(stream, true);
WorksheetPart worksheetPart = SpreadsheetReader.GetWorksheetPartByName(doc, "Sheet1");
WorksheetWriter writer = new WorksheetWriter(doc, worksheetPart);
Cell cell = writer.PasteDate("D3", new DateTime(2009, 12, 20, 15, 23, 05));
//Save to the memory stream, and then to a file
SpreadsheetWriter.Save(doc);
SpreadsheetWriter.StreamToFile(string.Format("{0}\\date.xlsx", GetOutputFolder()), stream);
}