#### Answer

$\approx0.3503$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
Use a calculator to approximate the value of the given expression, $
\log 643-\log287
.$
$\bf{\text{Solution Details:}}$
Using a calculator, the approximate value of the expression above is
\begin{array}{l}\require{cancel}
\approx2.80821-2.45788
\\\\
\approx0.35033
\\\\
\approx0.3503
.\end{array}