Let us say that you placed a $10 bet on the first dozen and won. You would be returned the original $10 wager plus $20 in winnings, or 2 to 1. Now let's say that you lost that same $10 wager. You would increase your bet 50 percent and wager a $15 sum on the first dozen.

If you won this bet, you would net $30, which covers the first $10 bet that you made, plus a net-net winning of the original $20 that you had hoped to win. Because we have to work in increments of $5, we cannot always increase the bet by exactly 50 percent, but it is close enough to keep a good account of things. If you had lost the $15 bet, you would have to choose between $20 and $25 for your next progression since you cannot bet $22.50 for an outside wager at the roulette table. The inverse progression rule works for all other bet types on the baize. You can work the other ones out for yourself.

Using any of the dozens or columns bets, let me show you how sellers of systems can accurately make claims that their system will win, for example, 85 percent of the time. This success percentage can be adjusted up or down depending on the particular bet's probability of hitting and the maximum number of successive bets chosen for the losing progression.