Is there a way to start Calc, taking the region as input and replacing it with the value?

[Marcin Borkowski]

Well, the subject is basically what I want.  I'd like to be able to
type, e.g., "2+3", mark it as a region, and press *something* only to
get it *replaced* by "5".

C-u C-x * g C-x * y q is pretty close, but not the same (and way too
long to be comfortable).

If there's no such thing, I could probably write it in Elisp myself,
but why reinvent the wheel?

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Adam Mickiewicz University