7 Seven
The design as a whole is to provide a randomly determined integer from one to six, each of those values being equally likely to militate against concerns that the faces of dice cause a small bias. For a single roll of a fairs-sided die, the probability of rolling each value is exactly 1/s-an of a discrete uniform distribution. For n multiple rolls, with an s-sided die, the possibility space is equal to sn. So, for n rolls of an s-sided die, the probability of any result is 1/sn. As the number of dice increases, the distribution of the sum of all numbers tends to normal distribution by the central limit theorem.
