Answer
0.20
Work Step by Step
$(5\times10^{6})(4\times10^{-8})$ $\longrightarrow$ associative property
=$(5\times4)(10^{6}\times10^{-8})$ $\longrightarrow$ multiply; add exponents if the base is the same
=$20\times10^{-2}$ $\longrightarrow$ move the decimal 19 places to the left
=$0.20$
