In a spreadsheet, Sheet0 is the first and farthest left sheet in a series of tabs and is a summary of all worksheets to its right. Adding cells from multiple sheets is easy enough when the sheets are known, but is it possible to add, for example, cell A5 across all sheets that are not Sheet0?
We have multiple contributors to the workbook, each will input their own page based on their sales results, if any, so we'll never know the number of sheets in a given period.
We're entering data into Google Docs spreadsheets, but the answer doesn't have to be product specific. Excel, Open Office, Google Docs, any would be fine.