6. A die is rolled twice. If the number of dots that appear on the first roll is $x$, and the number of dots that appear on the second roll is $y$, then the probability that the point $M(x, y)$ determined by $x$ and $y$ lies on the hyperbola $y=\frac{6}{x}$ is . $\qquad$
ii. $6 \cdot \frac{1}{9}$.
Point $M(x, y)(x, y \in\{1,2, \cdots, 6\})$ totals 36, among which, points $(1,6) 、(6,1) 、(2,3) 、(3,2)$ lie on the hyperbola $y=\frac{6}{x}$. Therefore, the required probability equals $\frac{1}{9}$.