Answer
$\color{blue}{5.12 \times 10^{-5}}$
Work Step by Step
Divide the corresponding parts (divide the constants together and the powers of 10 together) to obtain:
$=\dfrac{1.28}{2.5} \times \dfrac{10^{-8}}{10^{-4}}
\\=0.512 \times \dfrac{10^{-8}}{10^{-4}}$
Use the quotient rule for exponents to obtain:
$=0.512 \times 10^{-8-(-4)}
\\=0.512 \times 10^{-8+4}
\\=0.512 \times 10^{-4}$
Write $0.512$ as $5.12 \cdot 10^{-1}$ to obtain:
$=(5.12\cdot 10^{-1}) \times 10^{-4}
\\=5.12 \times 10^{-1+(-4)}
\\=\color{blue}{5.12 \times 10^{-5}}$
