The concept of the 666 strategy is to cover almost all of the numbers on felt with different size bets, adhering to the faulty thought that one of the numbers will always hit. The most popular variation of the 666 strategy is for the European Wheel variant and is below.

You will get 666. That's the summation of all the roulette numbers. You'll have noticed that the number is also famous under the name The Number of the Beast. Stereotypically, the number 666 represents the Devil. For that reason, many players refer to roulette as dancing with the devil or the Devil's Game.