In Excel it allows you to enter formulas using the mouse, by clicking on cells as you type a formula, instead on typing the cell references.
You can open a 2007 Excel spreadsheet with Excel 2003 if you save the file in Excel 2007 using "Save As" and select the 2003 compatibility mode.
Save the workbook as an Excel 2007 file instead of 97-2003 file.
over type mode
It depends. There is no direct relationship between Windows and Excel versions. If you have Windows XP, you probably use Excel 2003. If you have Windows 7, you probably use Excel 2007 or Excel 2010. Excel 2007 and later can read Excel 2003 files, but Excel 2003 cannot read Excel 2007 files, unless you save the files in "compatibility mode." Excel 2007 and later contain some features not available with Excel 2003 and earlier. If you need to use the same worksheets with several versions, then save your files in compatibility mode with the newer versions.
The status bar shows the current mode of Excel.
In Excel you can calculate the mode from the set of values by using the MODE function. If you wanted the mode from the range of cells from A2 to D50, then it would be:=MODE(A2:D50)
Usually there is no need to convert, since Open Office can read excel files (except Open Office probably will have problems with macros). If you have Excel 2007, then save the file in Office 2003 compatibility mode.
The Average function in Excel totals a range of cells and divides the total by the amount of values in those cells. In mathematics this is known as the Arithmetic Mean.