Prealgebra (7th Edition)

$(2.5\times10^{6})(2\times10^{-6})$ $\longrightarrow$ associative property =$(2.5\times2)(10^{6}\times10^{-6})$ $\longrightarrow$ multiply; add exponents if the base is the same =$5\times10^{0}$ $\longrightarrow$ if the exponent is 0 the result is 1 =$5\times1$ =$5$