Calling macros from a document

[MaxBass #I-D]

It's a question I haven't been able to answe by myself ;-)

In Excel you can do that.
For example define a macro:

public function getNumber long
getNumber = 10
end function

Then go to a cell and input
= getNumber()

And the "magically" the cell gets the number 10.

I tried to do the same in Word, inside and outside tables, but I
haven't been successful; and MSDN hasn't been helpful too.
I don't how to call a public function directly from the document (not
from VBA, from document) neither I know IF i can call such public
function.
May anybody help me please?

Thanks.