Which version of Excel do I have?

Excel 2007

Click the Office button then click Excel Options.
(Excel displays the Excel Options dialog box.)
At the left side of the dialog box, click Resources.
Click the About button.
(Excel displays the About Microsoft Office Excel dialog box and your version of Excel will appear there.)

—————

Excel 2010

Select the File tab from the Excel ribbon and then select Help.

Your version of Excel will appear under About Microsoft Excel.

—————

Excel 2013

Select the File tab from the Excel ribbon, then select Account > About Excel.

Your version of Excel will appear in the top line of the window.

—————-

Sources:

What Version of Excel am I Using?

http://excelribbon.tips.net/T008938_Determining_Your_Version_of_Excel.html