Chicago Sun-Times: Let's do the math on payback percentages

Q. Exactly what does it mean when a casino advertises that its payback percentage is such-and-such percent?

Dorothy M.

A. Each slot machine is scrupulously designed and tested to assure the casino a definite payback. The "payback percentage" is the portion of the money that is put into the slot that is eventually paid out to the player.

For example, with a payback of 95 percent, the casino would latch onto about 5 percent of all money put into the slot. You, Dorothy, should get back 95 cents of every dollar you insert. Of course, don't expect 95 cents to clang in the tray for every dollar's worth of pulls on the handle. The percentage return is a long-term concept. Your gaming timeline is possibly limited to 200 pulls, not millions, so any percentage return (as low as a goose egg to as high as a mega-jackpot) can, and will, happen. But, of course, if you knew ahead of time what the result was going to be, you wouldn't be playing, would you?

In most gambling jurisdictions, the law requires that payback percentages be above a threshold level, commonly around 75 cents. Fortunately, the payback percentage in most casino machines is much higher than the minimum, even some advertised as high as 98 percent- plus. It's those machines advertised for high paybacks that you want to play on. Leave the rest for the slow learners.

Q. How does a casino decide where to put the different slot machines on the casino floor?

Danny B.

A. Finding a home for each one-armed bandit is called "slot mix." Slot mix is casino nomenclature describing the physical placement of machines on the casino floor. Slot management places its machines strategically to maximize customer appeal and potential casino earnings.

Slot mix is composed of five basic variables: floor location, coin denominations, payoff schedules, casino advantage and payoff frequency. These variables can be blended into the casino floor in infinite variations, with no two casinos doing it exactly the same, but all striving to separate you from your hard-earned money.

Q. On my last casino visit, the following happened: Every blackjack hand for one hour totaled a 12-16 on my first two cards. Is this just bad luck or a slick dealer?

Tyler M.

A. Puh-leeeze, Tyler! Every single hand? This skeptical writer reflects that mathematically two-card hands totaling 12-16 occur 39 percent of the time, or about 2 out of 5 hands. More than 26 percent of the two-card hands will add up to 11 or less (for those interested in double-down possibilities, one-third of these will be 10 or 11). Finally, your first two cards will add up to a total of 17-21 35 percent of the time.

The only advantage your so-called "slick" dealer has is that all players must act on their hand before the dealer takes action on his.

Mark Pilarski writes a nationally syndicated gambling column. E- mail him at pilarski@markpilarski.com.