path of output node

Hello, i try to seek this information on the API and in forum but without success.

what is the path of out of a node?
e.g.
nodes[“Math”].outputs[0].(what i need to put here to get the float calculation value?)

i need to get a output from node to reuse into a drive single property

can you point me to a article or a API page to get clear in my mind.

many thanks, regards