  In recent years, we used lattice QCD to calculate some quantities that were
unknown or poorly known. They are the $q^2$ dependence of the form factor in
semileptonic $D\to Kl\nu$ decay, the leptonic decay constants of the $D^+$ and
$D_s$ mesons, and the mass of the $B_c$ meson. In this paper, we summarize
these calculations, with emphasis on their (subsequent) confirmation by
measurements in $e^+e^-$, $\gamma p$ and $\bar{p}p$ collisions.
