Answer
$6.3\times10^{7}$
Work Step by Step
$(3\times10^{4})$$(2.1\times10^{3})$
= $3.1\times2.1\times10^{4}\times10^{3}$
= $6.3\times10^{7}$
Group like terms and when multiplying exponents with the same bases, add the exponents and keep the base the same.
