Search notes:

Registry: HKEY_CURRENT_USER\Software\Microsoft\Office

List of subkeys I've seen below HKEY_CURRENT_USER\Software\Microsoft\Office include

Numerical sub keys

The numerical sub keys (such as 11.0, 12.0, 13.0) correspond to Office versions.
The actual value for a currently installed Office application is returned by the version property of the corresponding application object.
See also HKEY_CURRENT_USER\Software\Microsoft\Office\X.Y

Index