some , and is determined by The bet's expected net return, or profitability, is equal to Without details, for a bet, black (or red), the rule is determined as and the profitability . For similar reasons it is simple to see that the profitability is also equal for all remaining types of bets. . In reality this means that, the more bets a player makes, the more they are going to lose independent of the strategies (combinations of bet types or size of bets) that they employ: Here, the profit margin for the roulette owner is equal to approximately 2.7%. Nevertheless, several roulette strategy systems have been developed despite the losing odds. These systems can not change the odds of the game in favor of the player. It is worth noting that the odds for the player in American roulette are even worse, as the bet profitability is at worst , and never better than . Simplified mathematical model For a roulette wheel with green numbers and 36 other unique numbers, the chance of the ball landing on a given number is . For a betting option with numbers defining a win, the chance of winning a bet is For example, if a player bets on red, there are 18 red numbers, , so the chance of winning is . The payout given by the casino for a win is based on the roulette wheel having 36 outcomes, and the payout for a bet is given by . For example, betting on 1-12 there are 12 numbers that define a win, , the payout is , so the bettor wins 3 times their bet. The average return on a player's bet is given by For , the average return is always lower than 1, so on average a player will lose money. With 1 green number, , the average return is , that is, after a bet the player will on average have of their original bet returned to them. With 2 green numbers, , the average return is . With 3 green numbers, , the average return is . This shows that the expected return is independent of the choice of bet. Called (or call) bets or announced bets Although most often named "call bets" technically these bets are more accurately referred to as "announced bets". The legal distinction between a "call bet" and an "announced bet" is that