1. Let $N=99999$. Then $N^{3}=$
$$
\text { Two, 1.999970000 } 299999 \text {. }
$$

Since $N=10^{5}-1$, then
$$
\begin{array}{l}
N^{3}=\left(10^{5}-1\right)^{3}=10^{15}-3 \times 10^{10}+3 \times 10^{5}-1 \\
=10^{10}\left(10^{5}-3\right)+3 \times 10^{5}-1 \\
=999970000299999 .
\end{array}
$$