  The Littlewood-Richardson coefficients $c^{\lambda}_{\mu\nu}$ give the
multiplicity of an irreducible polynomial ${\rm GL}_n$-representation
$F^{\lambda}_n$ in the tensor product of polynomial representations
$F^{\mu}_n\otimes F^{\nu}_n$. In this paper, we generalize these coefficients
to an $r$-fold tensor product of rational representations, and give a new
method for computing them using an analogue of statistical contingency tables.
We demonstrate special cases in which our method reduces to counting
statistical contingency tables with prescribed margins. Finally, we extend our
result from the general linear group to both the orthogonal and symplectic
groups.
