[tex]\mathsf{(4 \times 10^4)(2\times 10^3)}\\\\\mathsf{= (4\times 10\times10\times10\times 10)(2\times 10\times 10\times 10)}\\\\\mathsf{= (4\times 100\times100)(2\times 100\times 10)}\\\\\mathsf{= (4\times \bold{10,000})(2\times \bf {1,000)}}\\\\\mathsf{= \bf (40,000)(2,000)}\\\\\mathsf{= 80,000,000}\\\\\mathsf{\approx 8\times 10^7}\\\\\\\huge\textbf{Therefore, your answer is: \boxed{\mathsf{8\times 10^7}}}\huge\checkmark[/tex]
[tex]\huge\text{Good luck on your assignment \& enjoy your day!}[/tex]
~[tex]\frak{Amphitrite1040:)}[/tex]
