2014 Cayley Problem 14

Storage space on a computer is measured in gigabytes (GB) and megabytes (MB), where 1 GB = 1024 MB. Julia has an empty 300 GB hard drive and puts 300\,000 MB of data onto it. How much storage space on the hard drive remains empty?

\textbf{(A)}\ 72 \text{ MB}\quad \textbf{(B)}\ 720 \text{ MB}\quad \textbf{(C)}\ 7200 \text{ MB}\quad \textbf{(D)}\ 7.2 \text{ GB}\quad \textbf{(E)}\ 72 \text{ GB}

If there are no answer choices shown, enter a numerical answer.

Full credit to this problem is given to the CEMC, you may view all Cayley contests here.