Answer
$3.24\times10^4$
Work Step by Step
Using $a\times10^n$, where $1\le a\le9,$ and $n$ is an integer, the scientific notation of the given expression, $
32400
,$ is
\begin{array}{l}\require{cancel}
3.2400\times10,000
\\\\=
3.24\times10^4
.\end{array}