#### Answer

9.6421

#### Work Step by Step

We know that logarithms to base 10 are common logarithms, and $log_{10}x$ is equivalent to $log(x)$.
Therefore, $log(10^{9.6421})=log_{10}10^{9.6421}$.
We know that for all positive numbers $a$ (where $a\ne1$), and all positive numbers $x$, $y=log_{a}x$ means the same as $x=a^{y}$.
Therefore, $log_{10}10^{9.6421}=9.6421$, because $10^{9.6421}=10^{9.6421}$.