using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using Bytescout.XLS;

namespace HelloWorld
{
class Program
{
static void Main(string[] args)
{
// Create new XLSDocument
XLSDocument document = new XLSDocument();

// Get worksheet by name
Worksheet worksheet = document.WorkBook.Worksheets.Add("Sample");

// Set header
worksheet.Cell(0, 0).Value = "Number";
worksheet.Cell(0, 1).Value = "Format";

// Set variables
double plan = 3000;
double result = 3100;

// Fill cells
for (int i = 1; i < 6; i++)
{
worksheet.Cell(i, 0).Value = result / plan;
}

// Set cells format
worksheet.Cell(1, 0).NumberFormat = "0.00";
worksheet.Cell(2, 0).NumberFormat = "0.00%";
worksheet.Cell(3, 0).NumberFormat = "mm:ss";
worksheet.Cell(4, 0).NumberFormat = "hh:mm:ss";
worksheet.Cell(5, 0).NumberFormat = "##0,0E+0";

// Set captions
worksheet.Cell(1, 1).Value = "0.00";
worksheet.Cell(2, 1).Value = "0.00%";
worksheet.Cell(3, 1).Value = "mm:ss";
worksheet.Cell(4, 1).Value = "hh:mm:ss";
worksheet.Cell(5, 1).Value = "##0,0E+0";

// Save document
document.SaveAs("Sample.xls");

// Close document
document.Close();

// open generated XLS document in default program
Process.Start("Sample.xls");
}
}
}

Download example source code: bytescoutxls_number_formatting_for_cells.zip (8 KB)