12. Two people take turns rolling dice, each rolling two 
at a time. The first one to get a sum greater than 6 on the two dice wins, otherwise the turn passes to the other person. The probability that the first person to roll wins is $\qquad$.
12. $\frac{12}{17}$.

The probability of the sum of the points on two dice being greater than 6
$$
\begin{array}{l} 
\text { is } \frac{21}{36}=\frac{7}{12}, \text { thus, the probability of the first player winning is } \\
\frac{7}{12}+\left(\frac{5}{12}\right)^{2} \times \frac{7}{12}+\left(\frac{5}{12}\right)^{4} \times \frac{7}{12}+\cdots \\
=\frac{7}{12} \times \frac{1}{1-\frac{25}{144}}=\frac{12}{17} .
\end{array}
$$