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Comment by krisrm | Hacker News Reader

The related article on blackjack (linked at the bottom) was also a great read. I've never felt like I really understood card counting but it makes a lot more sense now. Also explains why I don't go to the casino :)

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Card counting 101: unlike dice or roulette where every outcome is entirely independent, blackjack has "memory"... all the cards that have previously been discarded are unavailable in future hands. Blackjack starts out with a casino advantage of only about 0.3 to 0.7%. When a lot of 5s (and to a lesser extent, 6s and 4s) have been used already, that can move the advantage up to about 2 percentage points into the players favor, therefore, going from -0.5% to as high as +1.5%. The idea is to bet as little as possible under normal circumstances, and then for the hands where the advantage has shifted to the player, increase the bet as much as the casino will allow. So for example in theory, 40 hands x $10 x -0.5% + 3 hands x $500 x +1.0% is net positive. But not a lot, and good luck getting a 50x bet spread past a halfway decent pit boss.

> for the hands where the advantage has shifted to the player, increase the bet as much as the casino

...and your bankroll...

> will allow.

----

You can still go bust on a 1.5 % edge, after all, if you overbet.

If your bankroll isn't sufficient to withstand significant volatility, yes, you shouldn't start counting cards in the first place.

Just beware - the expected value of the authors simulated blackjack counting is quite good. This is due in part to the crazy “spread” (the ratio of max bet to min bet) of 100-to-1. This illustrates the profitability of the model well, but it’s unrealistic.

A more typical spread of 10-to-1 ekes out an expected value of ~0.5% (see https://wizardofodds.com/games/blackjack/card-counting/high-...). When I was counting, I could barely hit $15/hr expected value. Hardly worth the effort, I found it very demanding to keep track of the count at Vegas dealer speeds and play perfect blackjack for hours on end.

How did you manage to card count without attracting attention, even after playing for hours?

At $15/hour, I'm sure the casino will let them sit for days if they want. It's peanuts and shows other non-counters a player winning, meaning good publicity for the casino that's surely worth more than $15/hour.

Because he wasn't winning. Even if they noticed, he wasn't a threat.

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