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Craps Probability

A Little Probability For Beginners

The immutable laws of probability govern every game in the casino. Craps is no different. Very briefly, I will introduce two concepts that seem to be at odds, but co-exist in the universe of craps and probability.

First is the concept of an independent event. Every dice roll is an independent event. The chances of any particular outcome of an individual roll can be predicted with complete accuracy:

Outcome % Chance on Each Roll
2 2.77
3 5.55
4 8.33
5 11.11
6 13.88
7 16.66
8 13.88
9 11.11
10 8.33
11 5.55
12 2.77

The number of outcomes in a large number of rolls can also be predicted with a great amount of accuracy. Here is the predicted outcome of 100,000 rolls of a fair pair of dice, rolled fairly:

Outcome % Chance on Each Roll Predicted Outcome for 100,000 rolls (approx)
2 2.77 2,770
3 5.55 5,550
4 8.33 8,330
5 11.11 11,110
6 13.88 13,880
7 16.66 16,660
8 13.88 13,880
9 11.11 11,110
10 8.33 8,330
11 5.55 5,550
12 2.77 2,770

Every craps player should take these lessons from this: 1. Trends or streaks occur all the time at the craps table. They can be extremely profitable if you ride them. However, there is no way of predicting when they will begin or end.

2. If you haven't seen a certain number rolled in a long time, don't think the odds of that number being rolled are greater. If a 7 is rolled five times in a row, the odds of it appearing on the next roll are 1 in 6 (16.77%). This is because every roll is an independent event.