Roullete, also known as Roulette, is a casino game in which bets are placed on the outcome of a spin of a wheel. Players can choose to bet on a single number, various groupings of numbers, the color red or black, whether the number is odd or even, and if the number is high (19-36) or low (1-18). A winning bet is paid out according to its odds, and any unwinnable bets are collected. The croupier then spins the wheel and a small ball is dropped into it, which will ultimately come to rest in one of the compartments on the roulette table.
The earliest evidence of the game dates from the 17th century, and Blaise Pascal is often credited with inventing it. It gained a lot of traction in the 1800s as it spread from France to the casinos and gambling dens across Europe. The wheel itself consists of a solid wooden disk slightly convex in shape with a metal separator or fret around its circumference and containing thirty-six compartments painted alternately red and black and numbered nonconsecutively from 1 to 36. A 37th compartment, painted green on European-style wheels and red on American ones, carries the sign 0.
The symmetries in the layout of the numbers on the roulette wheel are interesting. The zero is on the same side as all the low red numbers, while the high black ones are on the other. A bet on the second or third dozen pays 2-1. This is a simple example, and there are numerous other bets that offer similar paytables. The game has spawned numerous betting systems that claim to improve a player’s chances of success. But, as the American mathematician Patrick Billingsley once said, “no betting system can convert a game with an imprecise and unbiased house edge into a profitable enterprise.”