What version of KDE do I have?

[Bruce Bales]

I installed Kubuntu 10.04-3.  How do I learn what version of KDE I 
have?  Seems logical
that the numbers are stored somewhere in a file.  Would the 10.04-3 
numbers be somewhere
in a file?

Is it possible to downgrade to another earlier version of KDE?  If so, 
Where could I find
instructions for how to do it?
bruce