1. As shown in Table 1, in the use of computers, codes are arranged according to certain rules, and they are infinite from left to right and from top to bottom. In Table 1, the code 100 appears $\qquad$ times.
\begin{tabular}{|c|c|c|c|c|c|}
\hline 1 & 1 & 1 & 1 & 1 & $\cdots$ \\
\hline 1 & 2 & 3 & 4 & 5 & $\cdots$ \\
\hline 1 & 3 & 5 & 7 & 9 & $\cdots$ \\
\hline 1 & 4 & 7 & 10 & 13 & $\cdots$ \\
\hline 1 & 5 & 9 & 13 & 17 & $\cdots$ \\
\hline$\cdots$ & $\cdots$ & $\cdots$ & $\cdots$ & $\cdots$ & $\cdots$ \\
\hline
\end{tabular}
From Table 1, we know that the $m$-th row is an arithmetic sequence with the first term 1 and common difference $m-1$. Therefore, the $n$-th number in the $m$-th row is
$$
\begin{array}{l}
a_{m n}=1+(n-1)(m-1) . \\
\text { Let } a_{m n}=100 \text {. Then } \\
(m-1)(n-1)=99=3^{2} \times 11 \text {. }
\end{array}
$$

The positive integer solutions are
$$
\begin{aligned}
(m, n)= & (2,100),(4,34),(10,12), \\
& (12,10),(34,4),(100,2) .
\end{aligned}
$$

Therefore, the code 100 appears 6 times in Table 1.