Answer
$1.2 \times 10^{-4}$
Work Step by Step
$a^m \cdot a^n = a^{m+n}$
Multiply the corresponding parts and use the rule above when necessary to obtain:
$=(0.4\cdot 3) \times (10^{0} \cdot 10^{-4})
\\=1.2 \times 10^{0+(-4)}
\\=1.2 \times 10^{-4}$
