If the spreadsheet program is any good, the calculations based on the entries in the spreadsheet will always be correct. In manual spreadsheets, the calculation is only as accurate as the person performing the calculation and as accurate as that person is in transcribing the results of their calculation.
Electronic spreadsheets do not occupy much space - just the space for the electronic storage media - thus you just need a decent hard drive to contain tens of thousands of spreadsheets instead of a room full of filing cabinets.
Sending a copy of an electronic spreadsheet to someone else just requires an internet connection and can be done almost instantly compared to mailing or faxing a copy of a manual worksheet
It is fairly simple to link the contents of one (or more) spreadsheet to another to perform additional calculations compared to digging out all the manual worksheets that might be needed and transcribing the information repeatedly for each separate piece of information.
