The parlay system is a very simple system for determining the amount to bet at roulette. Its essence is "let it ride". Make a bet, and leave the winnings there to ride on to the next bet.

This is not necessarily the entire amount. One line for the parlay system is called "31" in which you have a series which is:
1 1 1 2 2 4 4 8 8
(for a total of 31 units). The first bet is one unit. This can be anywhere from the table minimum to 1/16 of the table limit. This is not 1/8th because you must parlay the 8 units. If the bet wins, then you bet the same amount again. If it loses, you go up the series with a parlay on each bet. Note that if you win any of the parlays you will be winning from one to nine units