Answer
$0.000786$
Work Step by Step
Since the exponent of $10^{
-4
}$ is $\text{
negative }
4
,$ move the decimal point $
4
$ places to the $\text{
left
}.$ Hence, the given expression, $
7.86
\times10^{-4}
,$ is equivalent to
\begin{array}{l}\require{cancel}
0.000786
.\end{array}