How many people can share an excel file?

I think your question is 3 fold

how many people can access a particular file simultaneously

but
-how many can view simultaneously
-how many can enter data simultaneously

Excel is a flat file - spread sheet - only 1 person can enter data
the remaining people can view the file before the data was added - read ONLY
then when the 1st person saves the file with additional data
another user can open the file in a WRITE MODE

and for basic functionality u can access from different versions
you may be prompted for compatibility - depending on what was initially installed with the program

If your trying to enter data simultaneously you need a database
which multiple users can interact with and excel can be designed to pull the data into
various fields on the spreadsheet

You should consider document collaboration to achieve this.

http://office.microsoft.com/en-us/sharepoint-foundation-help/document-collaboration-and-co-authoring-HA101729921.aspx

One person can have it open in edit mode

Multiple people can have it open in read-only mode while one person has it in edit.

Technically, up to 256 users can be in a shared Excel workbook at once.

That said, the Expert consensus is that using this feature is not recommended.  For one thing, many of Excel's (and VBA's) best features are not available in shared workbooks.  More importantly, though, is that shared workbooks are much, much, much more prone to corruption.

I have joked before that there are only two kinds of shared workbooks: those that are corrupt, and those that soon will be.  That is an exaggeration, but not by much.

If you really need to enable multi-user support, a database is almost certainly a safer option.

perhaps I didnt ask the question correctly, but I know for sure that spreadsheets can be simultaneously worked on as I've done it before in the work place at a different firm.

The data in there is less than 100 rows and 10 columns wide, nothing too heavy and to be honest I doubt more than 2 or 3 people at any one time will have it open, if indeed more than one anyway.

matthew - does excel versions matter here?

Thanks.

Sharing, collaboration, multiple users in a spreadsheet is possible, but per the advice offered it is not recommended as the Excel spreadsheet will at some point become corrupt.

This link will offer various methods of collaborating/sharing an Excel document. You will need to locate the situation that pertains to your setup.

http://office.microsoft.com/en-us/excel-help/overview-of-sharing-and-collaborating-on-excel-data-HA010342753.aspx

http://www.google.com/search?q=shared+excel+file+corrupt&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1

Many anecdotes to support the shared Excel file corruption advice being offered. :) Best of luck!

how do I share an excel file in excel 2007 version?

Open the file, click Save As and select the XLSX file extension which is the 2007 version.

Then create a shared folder and put that file in it. Provide sharing to the appropriate people.

No, that's not what I am looking for.  I'm talking about the inbuilt feature within Excel to allow simultaneous editing.  Not a shared folder.  

Actually this is the link I was looking for.
http://support.microsoft.com/kb/269860