Two hundred thousand times two hundred thousand equals
$\text{(A)}\ \text{four hundred thousand} \qquad  \text{(B)}\ \text{four million} \qquad  \text{(C)}\ \text{forty thousand} \qquad \\ \text{(D)}\ \text{four hundred million} \qquad  \text{(E)}\ \text{forty billion}$
Writing the numbers in scientific notation, we have
\begin{align*} (2\times 10^5)\times (2\times 10^5) &= 4\times 10^{10} \\ &= 40\times 10^9 \\ &= \text{forty billion} \rightarrow \boxed{\text{E}}. \end{align*}