12. (10 points) $1^{3}+2^{3}+3^{3}+4^{3}+5^{3}+6^{3}+7^{3}+8^{3}+9^{3}=$
【Solution】Solution: $1^{3}+2^{3}+3^{3}+4^{3}+5^{3}+6^{3}+7^{3}+8^{3}+9^{3}$
$$
\begin{array}{l}
=(1+2+3 \cdots+9)^{2} \\
=45^{2} \\
=2025 ;
\end{array}
$$

Therefore, the answer is: 2025.