* But to help you better understand how this works, let’s look at an actual roulette scenario: *Say, for the sake of argument, that you bet $10 on 14 on a Double-Zero layout. Because there are actually 38 pockets on the wheelhead, your odds of losing are 37 to 1. But, assuming you do win this wager, the dealer will only pay you at a 35 to 1 ratio. So you’re total winnings on a $10 bet would be $350 instead of the $370 payoff that matches your actual risk.

The final sticking point to understanding roulette vigs, though, has more to do with probability than odds. Remember, we keep talking about a “percent advantage” here, and that’s because most people who pick apart games of chance do so using statistics. The reason for this is that probability is not a fractional ratio but an expression of the total possible outcomes. As a result, it can be converted into a percentage and these percentages can be multiplied to determine the probability of a string of events.

But to give it to you in plain English, **probability is the number of desired outcomes over the total number of possible outcomes.** So, if we go back to our six-sided die, you would have a 1 in 6 probability of winning because there is one possible way you can win and six total possible ways a die can land. This ratio can also be viewed as the fraction 1/6 or, if we divide one by six, the decimal .1666…. Also, we can find the percentage probability of an event by multiplying the decimal by 100—“percentage” literally meaning “per 100.” Doing that, we find out that the probability of winning our die roll is 16.66 percent or about 17 times out of 100.

So going back to that ever-confusing roulette vig, you can now see where all these percentages come from: If we figure that on an American Roulette wheel there are two pockets in 38 that aren’t counted in the payoff odds, we can divide that two by 38 and get .05263…. Then, by simply multiplying by 100, we find that the percentage probability of the ball landing in one of these pockets is 5.263!

This, of course, is only the crust on the casserole as far as roulette’s math goes, and we’ll definitely be giving you more numbers to crunch in later sections.