The Pivot system is a system of roulette for determining which number to bid on.

Spend some time at a roulette table prior to starting betting, and write down the winning number of each spin until one repeats. This repeating number is the 'pivot number'. Example:
12 23 33 36 29 7 8 12 4
Number 12 would be the pivot number for the next 36 spins unless it wins.

Bet the same amount on the pivot number for each spin until you either win or lose at the end of the 36th spin. A single number bet on roulette pays 35/1, and thus if the pivot number shows up anytime in the 36 spins you are a winner (or break even if it comes up on the last spin.)

When you have won, stop betting on that pivot number and select another one to start the process over again.

Why does it work? It is more likely to have some repeats in a run of 36 spins rather than perfect distribution of each number being hit once. On average, the same 24 numbers will appear in 36 spins of the wheel. This means that on average, for 36 spins there will be 12 repeated numbers. This could be one repeat of each of the 12 numbers, however it is more likely to be a repeat of a few numbers coming up three or four times each. This uses the theory of uneven distribution.