  We introduce two independent quantifications for 3-mode and 4-mode
entanglement. We investigate the conversion of one type of nonclassicality,
i.e. single-mode nonclassicality, into another type of nonclassicality, i.e.
multi-mode entanglement, in beam-splitters. We observe parallel behavior of the
two quantifications. The methods can be generalized to the quantification of
any multi-mode entanglement.
