Tracking and no tracking

4 January 2018

By John Grochowski

QUESTION: Why does tracking cards work in blackjack, but tracking doesn't work in other games? If it matters what happens in blackjack, why wouldn't it give you an edge to know how many rolls since the last 7 in craps or how many spins since the last bonus round on slot machines?

ANSWER: Counting cards in blackjack works because the odds are constantly changing. Unless the game uses a continuous shuffler, the cards from one hand are removed from play until the next shuffle.

Removing high cards from play decreases the percentage of high cards in the remaining deck, and that decreases the likelihood that you'll get blackjack or will draw a 10 on your double downs. Removing low cards while the 10s stay in the deck increases the likelihood of blackjack and of getting a 10 on your doubles.

In most other games, the odds are constant.

In craps, if it's been a long time between 7s, no one is changing the number of spots on the dice to make 7s more likely. The chances of a 7 on any given roll remain 1 in 6.

The random number generator on slot machines works from the same number set for every spin. No matter how long it's been since a bonus round, non-bonus results are not removed from the possible outcomes. The chances of reaching a bonus event are the same on every spin.

In card games such as Three Card Poker, Mississippi Stud and Caribbean Stud, there are no discards. The games are dealt from a freshly shuffled deck on every hand, so the odds are the same for every hand.

Baccarat does have a discard tray and the odds do change slightly as cards are removed from the remaining deck. However, the change in odds is so small that the late mathematician Peter Griffin calculated a card counter would have to watch hand after hand while making only three bets per eight hours to grind out a small edge.

That leaves blackjack as a game of changing odds in which card counters can gain an edge, baccarat with minutely changing odds that make card counting impractical, and a whole lot of games in which the odds are the same on every play and tracking results makes no difference.


QUESTION: I was at the players' club booth and overheard a loud, heated conversation between a supervisor and a lady who was furious that her points had been deleted. It seems she'd forgotten her card in a machine and got a new one, then forgot that one, too, and got another new one.

The club deleted points not only on those machines, but points the woman already had on account. That doesn't seem right. Can they do that?

ANSWER: Yes, the club can deduct the points, but there may have been more to the story than you observed.

Did the player have a pattern of leaving cards in machines, perhaps in the hope of reaping points from the play of others?

I once had a marketing manager tell me of a player who on multiple occasions left cards in $5 slot machines without playing, then set off to play penny slots. The players club concluded he was trying to get an unearned points boost from big bettors, while betting small himself. The player was stripped of points and benefits, and barred from the club.

Did you encounter a forgetful player who accidentally left her card behind a couple of times, or a points hustler trying to get something for nothing? The answer makes a huge difference in how the club handles the situation.