8. Given $a=1+2+\cdots+2004$. Then the remainder when $a$ is divided by 17 is
8.1.
$$
\begin{array}{l}
a=1+2+\cdots+2004 \\
=\frac{2004 \times 2005}{2}=2009010 .
\end{array}
$$

Then 2009010 divided by 17 gives a quotient of 118177, with a remainder of 1.