By default, Excel 2010 include 3 worksheets in a workbook. If you need to work on more than 3 worksheets, you can change the number of sheets to be included in new workbook. This post covers how to change default number of included sheets.
To change the default number of sheet in Excel, On File menu, Click Options.
This will bring up Excel Options dialog, now under main window, enter the sheets number from Include this many sheets options.