This exact same idea applies to all the probabilities in American roulette (thanks to that extra 00 number), just on a slightly bigger scale.įact: This difference in the probabilities also has a knock-on effect for the house edge too. Now, if I added another green ball so that there are now 2 green balls in the bag, the probability of picking out a red ball has dropped to 1 in 4. If I ask you to pick out one ball at random, the probability of choosing a red ball would be 1 in 3. To give a simplified example, lets say I have a bag with 1 red, 1 black and 1 green ball in it.

Therefore, the presence of this additional green number ever so slightly decreases the probability of hitting other specific numbers or sets of numbers, whether it be over one spin or over multiple spins. The probabilities in American and European roulette are different because American roulette has an extra green number (the double zero - 00), whereas European roulette does not. Why is there a difference between European and American roulette? The 0 or 00 appearing at least once over 10 spins.ģ. This is not because the American wheel is 'fairer' and dishes out red/black colors more evenly - it's because there is an additional green number (the double zero - 00) that increases the likelihood of disrupting the flow of successive same-color spins. You'll also notice that it's less likely to see the same color appear on multiple spins in a row on an American roulette wheel than it is on a European wheel. The probability of seeing the same color appear on successive spins just over halves from one spin to the next. Number of SpinsĮxample: The probability of the same color showing up 6 times in a row on an American roulette wheel is 1.13%.

The 0 appearing at least once over 10 spins.Ī graph to show the probability of seeing the same color of red/black on an American roulette table (compared to the odds on a European table). I stopped the graph at 6 trials/spins, as that was enough to highlight the trend and produce a prettier probability graph. Number of SpinsĮxample: The probability of the same color showing up 4 times in a row is 5.60%.Īs the graph shows, the probability of seeing the same color on consecutive spins of the roulette wheel more than halves (well, the ratio probability doubles) from one spin to the next. A graph to show the probability of seeing the same color of red/black (or any evens bet result for that matter) over multiple spins.

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