C#打印问题

 private static void printDoc_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
        {
            int i;
            int nWidth;
            int nTop = e.MarginBounds.Top;
            int nLeft = e.MarginBounds.Left;
            DataRow prow = projectTable.Rows[0];
            try
            {
                //if (PrintFont == null) PrintFont = dg.Font;                // Before starting first page, it saves Width & Height of Headers and CoulmnType
                if (PageNo == 1)
                {
                    int cc = constructTable.Columns.Count - 1;
                    nWidth = (int)(Math.Floor((double)1 / (double)cc * (double)e.MarginBounds.Width));
                    nHeight = (int)(e.Graphics.MeasureString("项目名称", PrintFont, nWidth).Height) + 0;
                    for (int q = 0; q < cc; q++)
                    {
                        ColumnLefts.Add(nLeft);
                        ColumnWidths.Add(nWidth);
                        nLeft += nWidth;
                    }
求这行什么什么意思：nWidth = (int)(Math.Floor((double)1 / (double)cc * (double)e.MarginBounds.Width));