Frenchmen Francois and Louis Blanc invented roulette with a single zero in 1842. They removed the double zero from the wheel and haphazardly rearranged the numbers 1 to 36. Despite removing one of the pockets, they kept the payout odds for a winning number at 35/1. This cut the house advantage to just 2.7 per cent, which proved extremely popular with gamblers. Since gambling had been made illegal in France in 1837, they introduced the game to Bad-Homburg in Germany. It was a great success. When gaming was outlawed in Germany, Francois and his son Camille brought the game to Monte Carlo.
In 1857 Prince Charles III of Monaco decided to introduce gambling to the principality to boost its finances. Gambling had just been outlawed in Germany. This prompted Leblanc to bring his game of single-zero roulette to Monte Carlo. Monte Carlo had the monopoly on roulette until 1933.