Expanding on previous columns

I try as best I can to make this column easy to understand, but every now and again I receive an e-mail from a reader that makes it apparent I have to give a few explanations.

Take this e-mail, from a Colorado reader:

"Hey John, what the heck do you mean by '9/6 Jacks or Better'? What do the numbers mean? I've also noticed that when you write about video poker, you'll say something about a '6-for-1' payoff. Is that the same as '6-TO-1'? Explanations, please.

9/6 Jacks or Better: The numbers in front of video poker games usually refer to payoffs on full houses and flushes. The most common way of changing payback percentages on video poker is to change payoffs on those hands. So 9/6 Jacks or Better, which returns 99.5% with expert play, pays 9-for-1 for full houses and 6-for-1 on flushes, while 8/5 Jacks or Better, a 97.3% game, pays 8-for-1 on full houses and 5-for-1 on flushes.

The numbers aren't part of the name of the game on the machine. When you look at the game options, the screen or glass will just say "Jacks or Better." It's up to you to check the pay table.

Payback percentage: The percentage of all money dropped into a slot or video poker machine that it returns to players. If a casino tells you its slots return 94%, that means for every $100 played, the machine paid out $94 and the casino kept $6.

That doesn't mean every player will get back $94 for a $100 bill — if it did, nobody would play. Why not just hand over $6? Some players will get back much more than their original $100, others will get back much less.

When discussing specific video poker machines, in which strategies and payback rates can be calculated, the figures used are theoretical payback percentages with optimal play. That is, a machine that I say has a 99.5% payback percentage in the long run will return $99.50 for each $100 played to someone who plays at expert level. Most players will get back a couple of percent less.

Odds-to-1 vs. odds-for-1: If you see "for" in the middle, it's a signal that you're not keeping your original wager in addition to your payback. If your video poker game pays 9-for-1 on a full house and you wager one coin, that bet is subtracted from the credit meter, then the full house adds nine credits. Your 9-for-1 payback is a profit of eight coins.

That's the same as an 8-to-1 payoff. In roulette, if you bet a chip on a four-number corner and win, you keep your original chip and get eight more in winnings.

The effect is the same, whether we call it 9-for-1 or 8-to-1. We've wagered one coin or chip, and after it's all over, we have nine, eight of which are profit. Referring to the video poker payoff as 9-for-1 better reflects what you see on the pay table instead of translating to 8-to-1, or just 8-1, which is the common usage on most table games.

Double down: In blackjack, to double your original bet after your first two cards. If you double down, you receive only one more card.

Split pairs: Also in blackjack, if your first two cards are the same denomination, you may make a second bet equal to your first. Each card then becomes the starting point for a separate hand.

Random number generator: In slot machines and other electronic gaming devices, the computer program that determines what reel combination, or poker or blackjack cards, or keno numbers will show up on the screen. The outcome of each pull is designed to be randomly chosen, so that it's possible the big jackpot combination could show up twice in a row, or not at all for tens of thousands of pulls.

House percentage; house edge: The percentage of money wagered the house expects to keep in the long run. In the short term, anything can happen, but over hundreds of thousands of plays, the odds of a game are set so the house will come very close to a specific percentage.

In roulette, the true odds on winning a single-number bet are 37-1, but the payoff is 35-1. The difference is the house edge, which we usually express as a percentage. In this case, a bet that would leave the player with 38 units if paid at true odds leaves him with only 36, a difference of two units in favor of the house. Divide 2 by 38, then multiply by 100 to convert to percent, and you get the house edge on this bet — 5.26%. In the long run, the house can expect to keep $5.26 for every $100 wagered.

The house percentage on table games is just the inverse of the payback percentage on slot machines. A house percentage of 5.26% at roulette is equivalent to a payback percentage of 94.74% on a slot machine.