The casino game craps is based on rolling two dice. Here is the assignment of probabilities to the sum of the numbers on the up-faces when two dice are rolled:

Outcome	2	3	4	5	6	7	8	9	10	11	12
Probability	1/36	2/36	3/36	4/36	5/36	6/36	5/36	4/36	3/36	2/36	1/36

The most common bet in craps is the "pass line". A pass line bettor wins immediately if either a 7 or an 11 comes up on the first roll. This is called a natural. What is the probability that a natural does not occur?