$$
\begin{array}{l}
\frac{1}{2}+\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{1}{4}+\frac{2}{4}+\frac{3}{4}\right)+\cdots+ \\
\left(\frac{1}{2006}+\frac{2}{2006}+\cdots+\frac{2005}{2006}\right)
\end{array}
$$
(Hint: Use the holistic idea, set the original expression as equation (1). Rearrange the terms inside the parentheses in reverse order to get equation (2). (1) + (2) yields the result. Answer:
$$
\left.\frac{2011015}{2} .\right)
$$