This is a sub-story to my Vegas story. I had a brief encounter with a guy I'm pretty sure was counting cards.
Now, I've always been interested in the odds and the math behind games (not just card games). So naturally, I'm interested in card counting. One of the great things about blackjack is that it is one of the only games in Vegas that has a memory. I have argued several times with a friend about probability and independent events. His idea on roulette was to watch the history and if several reds had hit, to bet on black. But each spin of the wheel is independent from the last spin. The same with dice. If I flip a coin 1 time, the probability of it landing on heads is 50%. If I flip it 10 times and it lands on tails all 10 times, what is the probability of the next flip being heads? It's still 50%. While I was playing roulette one day (and yes, even though I know it's mathematically inconsisitent, I still found myself watching the history and betting based on the past ), I saw 5 numbers in a row hit in the 30s and it hit 33 twice in a row during that run. That seems improbable, but statistically, it was just as likely to hit 33 the 2nd time as it was the 1st time.
My encounter with the assumed counter was during my Monday night blackjack marathon. It was early in the night because I was still sitting in the middle of the table. This Asian guy was standing behind us just watching the game. There were open seats, but he didn't want to play. He just stood and watched, he didn't seem to know anyone at the table. About 3/4 through the shoe, he decides to sit down. He cashes in a C-note and places all $100 in the circle. Damn, dude is serious. I've seen people do stuff like this before, but they didn't sit down, they walked up put their money down, either lost or won and walked off. Lo and behold, the dealer busts and this guy is $100 richer. His next bet was only $15. Now that's a big change in betting strategy. He lost. Next hand, he lays out $25 and wins. It starts dawning on me that he was back-counting the whole shoe (when you count the cards while not sitting at the table) and he waited til there was a high positive count to sit down. The next hand he lays out $50, I had just won $10, so I left it out there for $20. We both won. He leaves $50 out there, I put out $30 and won. When we finished the shoe, he got up and left. I won about $75 in the 3 or 4 hands where I watched what he bet before making my bet.
The process of counting cards is simple. Statistically, more low cards favors the house while more high cards favor the players. So, you don't actually count the cards that are played (meaning you don't have to know that 4 Kings, 2 fives and 3 10s have shown up), you just keep a running count of the high and low cards. Low cards (2 - 6) are worth +1 point, high cards (10 - Ace) are worth -1 point. 7, 8 and 9s are neutral. When the count is positive, that means it is more likely for high cards to come out, favoring the player. So the idea is to adjust your bet according to the count. If it is negative, you bet the minimum, if it is positive, you bet more ( raising the bet for higher positive counts).
Now, if you go to Vegas and you count the cards down at the table and you are fluctuating your bet drastically based on the count, you will stand out like a turd in a punchbowl. Trust me, they've seen it all before. One of the ways counters have gotten around this is by working in teams. You can have several people sitting at various tables, just betting the minimum and counting. When the count gets high enough, instead of them changing their bet, they signal to a partner and he or she comes in and just starts betting big. Since he hasn't played any other way, it's not as suspicious. When the count goes down, that player leaves.