  Based on the NRQCD factorization formalism, we calculate the inclusive charm
production rate in Upsilon(nS) decay at leading order in the strong coupling
constant alpha_s and the relative velocity v of the b quark in the quarkonium
rest frame. The branching fractions for Upsilon(nS) to charm for n=1, 2, and 3
are all around 7-9%. About 60% of the branching fraction into charm is from
annihilation of the color-singlet bb-bar pair into gamma^* -> cc-bar. Most of
the remaining branching fraction is from annihilation of the color-singlet
bb-bar pair decaying into cc-bar gg. We also compute the momentum distributions
of the charm quark and charmed hadrons in the decays. The virtual-photon
contribution to the charm quark momentum distribution is concentrated at the
end point while the cc-bar gg contribution is broad. The momentum distributions
for charmed hadrons are obtained by convolving the charm-quark momentum
distribution with charm fragmentation functions. This makes the momentum
distributions for charmed hadrons softer than that for the charm quark. This
effect is particularly significant in the virtual-photon contribution.
