One of the many different tactics and strategies for financial success is one that stands out – the doubling trick. It is advertised in many videos on the World Wide Web. Words like “risk-free” and “guaranteed” are often used in the descriptions of such roulette strategies.

**This is how the doubling trick works**

The principle of the so-called doubling trick looks very simple. We expressly start from classic French roulette. There are a total of 37 fields on the roulette table. Of these, 18 are red, and 18 are black. A single field with the digit zero is shown in green. Players have the option to bet on the color of the drawn ball. The probabilities for the colors red and black are 48.6 percent each. Promotional videos speak of “almost 50 percent”, you can simply round up.

Now players with a certain part of their total capital should bet on the appearance of a color. In the example, let’s assume an amount of 10 dollars. If a gambler puts these 10 dollars on the color red and wins in a game, 20 dollars will be paid out to him. For the next round, he again bets 10 dollars on the color red. This principle continues until he loses. The bet is doubled, and the next game is bet on the color selected at the beginning (in this case, red). So the bet is 20 dollars in red. If a red number is played, the player receives a payment of 40 dollars and has thus made up for his loss from the previous game and won an additional 10 dollars.

In the second game, if another color is the winning coloring, the doubling principle is continued. For the next spin in the roulette wheel, the gambler must have already bet 40 dollars on one color. The doubling continues until a profit has been made. Then the trick starts again with the specified starting capital – in this case, 10 dollars. The foolproofness of the doubling trick is justified by the fact that the selected color has to follow at some point purely statistically.

**So the doubling trick is nonsense**

The first glance should be directed to the statement of “approximately 50 percent”. A 1 to 2 chance sounds promising, but it’s not the truth. Even the smallest percentages should not be ignored in professional probability calculations. The fact is that with a 2.8 percent chance, the number zero, and thus a green field can be achieved. The first minor mistake of the doubling trick is thus quickly exposed and, above all, shows the manipulation of the interested gambler who is simply being exposed to untruths.

It sounds logical and easy to understand: if a certain color has been drawn again and again with a probability of 48.6 percent, the chances that another color will win in the next game increase emotionally. In reality, however, this is expressly not the case. Each play must be viewed as a single event. The probabilities are always the same and do not change due to the achievement of certain results in the previous game. Even if ten consecutive games have always been played in red, there is a 48.6 percent chance that the next spin will result in a black digit. High series of the same color in a row are only emotionally unusual. From a purely statistical point of view, rows are nothing special.

When explaining why the doubling trick is guaranteed to work, two models of the probability calculation are often confused. It is assumed that one color’s appearance in one game increases the likelihood of another color appearing in the next game. One event affects the other and changes the probabilities according to the stochastic model “without replacement.” If the respective drawn digit disappeared from the roulette wheel after a drawing, this way of thinking would be correct. However, this is not the case in the present case. The doubling trick is, therefore, not applicable. Apart from that, the player capital cannot hold large doubles very quickly. The sums to be bet are increasing very rapidly.