The number of spreadsheets is basically limited by the size of your computer memory. As a general rule, it is not a good idea to have to many, and it is a bad way to use a spreadsheet. It can be easier to use different workbooks for different things rather than having too many sheets in one workbook. Another disadvantage is that if the one file with everything in it gets damaged, then you have lost everything. If your work is in several files and you lose one, you have not lost everything.
The maximum number of sheets in an Excel 2007 workbook is governed by available memory. To see available memory in Excel, open Help and type in "specifications."
The maximum number of Worksheets can be inserted in excel 2003 or earlier is 255 sheets.
According to Microsoft: The maximum number of worksheets is not defined in Excel, but external factors, such as memory and disk space, might causes limitations to be applied.
In Excel 2007 you can add as many worksheets as you like, limited by the memory available to your computer, since all worksheets must reside in memory at the same time. When you first start Excel, the default is three pages available, but if you click on one of the page tabs, you can add more sheets.
With Excel 2007, there are three default worksheets that open with a new worksheet. The total number of worksheets possible in a single Excel 2007 workbook are limited only by the amount of memory in your computer, since all worksheets must reside in memory at the same time.
The number of worksheets in Excel 2007 and higher is limited only by the amount of computer memory available to Excel.
The default amount of sheets a workbook is created with is normally three, but this can be changed in ythe excel settings.