However, casinos aren’t interested in offering zero expectation games. In order to make a profit, they need to add in those two extra green numbers to change the odds in roulette. Now, when you bet red or black, your odds of winning are % rather than % So your even money bet moves from a zero expectation to a negative expectation.
Wheneyer you’re the underdog (such as in roulette), your wager has a negative expectation, and you can expect to lose money. It may not happen right then. You may defy the bad odds for a while and win, but over time you will lose.
Most bets carry a negative expectation because the house doesn’t give true odds for the payouts (as is the case for roulette). Craps provides another good example. Say you bet that the dice will total seven on the next throw. If you win, you are paid 4 to 1. However, the true odds for this occurrence hap¬pening are 5 to 1.
That difference may not sound like a major change, but the house edge on that bet is a whopping 16.67 percent! And a negative expectation bet for you is a positive for the casino. (The casino makes an average of $16.67 on every $100 bet in the previous craps example.)
