16. (10 points) If $48 a b=a b \times 65$, then $a b=$
【Solution】Solve: $48 a b=a b \times 65$,
$$
\begin{aligned}
a b \times 65-48 a b & =0, \\
17 a b & =0, \\
a b & =0 .
\end{aligned}
$$

Therefore, the answer is: 0 .