how to open Excel,
and that the cell's styling will be Number with no numbers after the dot (.)
for example: the number 1234567890 will show 1234567890 not 1.23E+09
thank's in advance
If the number format of the cells are correctly set already, you can do this using the AutoFit command.
Worksheet worksheet = (Worksheet)workbook.ActiveSheet;
Range usedRange = worksheet.UsedRange;
usedRange.Columns.AutoFit();
Have a look here
How to automate Microsoft Excel from Microsoft Visual C# .NET
you can read excel file like an access database with OleDB. then you can fill data into DataTable and work with it.