## Thinking Mathematically (6th Edition)

$40$
Divide the corresponding parts to find: $=\dfrac{2.4}{6} \times \dfrac{10^{-4}}{10^{-6}} \\=0.4 \times 10^{-4-(-6)} \\=0.4 \times 10^{-4+6} \\=0.4 \times 10^2 \\=4 \times 10^{2-1} \\=4 \times 10^1\\=40$