  We calculate the semileptonic branching ratio and the charm counting of
inclusive $B$ meson decays using the perturbative QCD formalism. For the
nonleptonic decays, we employ the modified factorization theorem, in which
Wilson coefficients evolve with the characteristic scales of the decay modes.
It is found that the decay rate of the single-charm mode $b\to c{\bar u}d$ is
enhanced, and a lower $B_{SL}$ is obtained without increasing $n_c$. We predict
a larger $b\to c \tau \bar{\nu}$ branching ratio compared to that from the
conventional heavy-quark-effective-theory based operator product expansion. Our
result of the $B$ meson lifetime is also consistent with the data.
