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How Does Counting Cards in Blackjack Work?

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Owning a casino isn't much of a gamble. In almost every game, the casino has a statistical advantage—so for every one gambler raking it in, there are more than enough people leaving with empty pockets to net an enormous profit. But between the rolling dice and spinning roulette wheels, there’s one game—if played with the right strategy—where the odds are actually in the gambler’s favor. That game is blackjack. You just have to learn how to count cards.

Blackjack, also called twenty-one, is one of the most popular casino games in the world. In this push-your-luck card game, you attempt to beat the dealer at getting as close to 21 points worth of cards. While the dealer always has to follow a simple set of betting rules, the gambler is free to pursue the best strategy available. And despite popular belief, with enough practice, anyone can count cards in blackjack; you don’t have to be a genius, and although it’s called "counting cards," you’re not memorizing which cards have been played. Here’s why and how it works.

The Theory

In a normal game of blackjack played with a single deck of cards, the "house edge"—the statistical likelihood that the casino will come out on top—is essentially nil. That means that if you play according to the very best strategy available (by memorizing and following the optimal method), in the long-run you’ll break even. That doesn’t sound like much, but blackjack is the only table-game that can claim such advantageous odds. And it’s these odds that make blackjack ripe for card counting.

In simple terms, "counting cards" just means keeping a tally of certain cards while the dealer burns through the deck. By keeping that tally—although you still play with the same strategy as before—you know approximately which cards are more likely to come up for both you and the dealer in the next hand.

And that little bit of information can tell you when to bet big, or when to bet small. Having more low-numbered cards left in the deck is bad. It means you’re less likely to get a blackjack (21 points on your first two cards, which pays a bonus) and the dealer is less likely to "bust"—get over 21 points worth of cards—due to the dealer’s rigid betting rules. And more high-numbered cards are good for the opposite reasons.

If played correctly, counting cards improves your odds by around 1 percent. Again, that doesn’t sound like much, but over many, many hours and even more hands of cards, you can count on netting in the green.

In Practice

There are more than a few card counting strategies, but perhaps the best and easiest is a system called High-Low.

Using the High-Low strategy, the card counter only has to keep a simple mental tally of three groups of cards. Every time he or she sees a high number card played on the table (the 10s and all the face cards), the counter subtracts 1 from his or her tally. For every low number card (the twos through sixes) the counter adds 1 to his or her tally. The middle cards (the sevens, eights, and nines) are simply ignored.

If, for example, the running tally is at +3, that means the upcoming cards are more likely to be high, and thus it’s advantageous for the player to bet big. If the tally is at -2, the odds are on the dealer’s side because of the forthcoming low cards, and so it’s best to bet small. And when the deck is shuffled, the count goes back to 0.

With enough time, this straightforward tally becomes effortless. But the key to success is practice. Card counting is a long-term strategy, and keeping your 1 percent edge requires playing by the book game after game, while keeping count of what cards are rapidly being dealt and flipped on the table. And in a bustling casino brimming with coming and going players, that means staying focused.

Not Getting Caught

Despite what any casino would like you to think, card counting is not illegal. You’re not cheating—you’re simply out-thinking the house. But casinos know that card counters can and will lose them money. And they take advantage of their right to deny service to anyone they please by searching for and kicking out suspect gamblers.

From a casino’s perspective, a telltale card counter is someone who’s hyper-focused on the game, and plays for long stretches of time, and bets amounts that vary wildly and seemingly randomly (as the odds swing in or out of the card counter’s favor). But there are a few ways you can fool the casino.

First, don't look the part. Dress like a tourist, chat with the dealer, and take your time when betting—normal players don’t have a betting strategy drilled into them. This is also where your card counting practice will help, because if keeping your tally becomes truly effortless, small-talk won’t derail your work.

Second, vary your bet minimally. While this decreases your advantage, it increases your card counter camouflage. Doubling or tripling your bet suddenly is the quickest way to flag yourself, and not only will that draw unwanted attention, but the dealer will likely shuffle the deck, ruining your count. So try to fly under the radar of the pit bosses and ever-present eyes of the casino’s security.

Lastly, don’t stay at one casino or one table for too long. As a card counter, you’re now the only (legal) snag in a casino’s otherwise solid business strategy—a wandering statistical anomaly—so take your show on the road.

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Do 'Close Door' Buttons in Elevators Actually Do Anything?
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When you’re running late for work, one small comfort is finding an empty elevator waiting for you at your office building. You scurry inside, and since no one else is waiting to enter, you jab the 'close door' button. The doors comply, the elevator starts moving, and you breathe a sigh of relief.

This is a familiar scenario for many, but it’s also a big fat lie. That’s because most of the door-close buttons in U.S. elevators don’t actually work. In fact, they’re programmed that way.

But before you get ready to send off a strongly worded email to your office building’s elevator manufacturer, you may want to hear why this is the case. When the Americans With Disabilities Act was first passed in 1990, certain requirements for elevators were outlined, such as the installation of raised buttons, braille signs, and audible signals.

The act ensured that someone with a disability would have enough time to get inside, stipulating that elevator doors must remain fully open for at least three seconds and thereby preventing the button from cutting that time short. Some elevator manufacturers took it one step further by deactivating the button entirely.

Since the life span of an elevator is about 25 years and the Disabilities Act has been around for 28 years, it’s safe to assume that most of the elevators in operation today do not have a functioning 'close door' button, The New York Times reports. Only firefighters are able to close elevator doors manually through the use of a key.

It's important to note that there are exceptions to this rule, though. As the New York Daily News noted, New York City elevators are required by law to have working 'close door' buttons, even though some operate on a long delay (so long, in fact, that it calls the button's usefulness into question).

However, you’re in luck if you’re taking a lift (which, of course, is British for “elevator”). 'Close door' buttons are fully functional in most elevators in the UK, according to The Telegraph. A spokesman for the Lift and Escalator Industry Association told the newspaper that not all elevators have the button, but when they’re present, they do work. Again, the time it takes for the doors to shut after pressing the button varies from lift to lift.

While U.S. elevator manufacturers have a seemingly good reason for disabling the 'close door' button, some may question the point of propagating the myth and installing a button that serves no purpose in the first place. In response, some would argue that placebo buttons serve an important psychological function in society.

"Perceived control is very important," Harvard psychologist Ellen J. Langer told The New York Times. "It diminishes stress and promotes well-being."

That’s right: By believing that you’re in control of your fate—or at least how quickly you can make it up to the sixth floor—you’re better off. It doesn’t end with elevators, either. Buttons placed at city crosswalks are often disabled, and the thermostats in many office buildings are rigged so that the temperature can’t be altered (even if the numbers appear to change).

Some might swear up and down that elevator 'close door' buttons work, but this, too, could be your brain deceiving you. As author David McRaney wrote in an essay: “If you happen to find yourself pressing a nonfunctional close-door button, and later the doors close, you’ll probably never notice because a little spurt of happiness will cascade through your brain once you see what you believe is a response to your action. Your behavior was just reinforced. You will keep pressing the button in the future.”

According to The New Yorker, these buttons are designed to alleviate some of the subconscious anxiety that comes from stepping inside a tiny box that's hoisted up some 20 or 40 or 80 floors by a cable: “Elevator design is rooted in deception—to disguise not only the bare fact of the box hanging by ropes but also the tethering of tenants to a system over which they have no command."

So now you know: Next time you’re running late to work, take comfort in the fact that those few extra seconds you would’ve saved by pressing a functioning 'close door' button aren’t worth all that much in the long run.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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What’s the Difference Between Prison and Jail?
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Many people use the terms jail and prison interchangeably, and while both terms refer to areas where people are held, there's a substantial difference between the two methods of incarceration. Where a person who is accused of a crime is held, and for how long, is a factor in determining the difference between the two—and whether a person is held in a jail or a prison is largely determined by the severity of the crime they have committed.

A jail (or, for our British friends, a gaol) refers to a small, temporary holding facility—run by local governments and supervised by county sheriff departments—that is designed to detain recently arrested people who have committed a minor offense or misdemeanor. A person can also be held in jail for an extended period of time if the sentence for their offense is less than a year. There are currently 3163 local jail facilities in the United States.

A jail is different from the similarly temporary “lockup”—sort of like “pre-jail”—which is located in local police departments and holds offenders unable to post bail, people arrested for public drunkenness who are kept until they are sober, or, most importantly, offenders waiting to be processed into the jail system.

A prison, on the other hand, is usually a large state- or federal-run facility meant to house people convicted of a serious crime or felony, and whose sentences for those crimes surpass 365 days. A prison could also be called a “penitentiary,” among other names.

To be put in a state prison, a person must be convicted of breaking a state law. To be put in a federal prison, a person must be convicted of breaking federal law. Basic amenities in a prison are more extensive than in a jail because, obviously, an inmate is likely to spend more than a year of his or her life confined inside a prison. As of 2012, there were 4575 operating prisons in the U.S.—the most in the world. The country with the second highest number of operating prisons is Russia, which has just 1029 facilities.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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