Answer
$1.2\times10^7$
Work Step by Step
We start with the given expression: $(4\times10^7)(3\times10^{-1})$
We use the associative property of multiplication to regroup the factors in a different way: $(4\times3)(10^7\times10^{-1})$
We multiply the constants: $12(10^7\times10^{-1})$
To multiply powers with the same base, we add the exponents: $12(10^{7+(-1)})=12\times10^{6}$
We rewrite this in scientific notation: $1.2\times10^7$
