The 666 system is an aggressive online roulette betting strategy but fairly low risk. It is similar to the cover-the-field system where you bet on as many numbers as you can. By betting on so many numbers at once, the theory goes, the chances of making a small profit is greater.

In most casinos, the payout for a winning bet on 0 is 35 to 1, meaning you receive 35 times your original bet. This can result in a significant win if you've placed a substantial bet on 0. However, it's important to note that the odds of the ball landing on 0 are relatively low, so it's considered a high-risk bet.

The 0  (single zero) and the 00  (double zero) are the green slots on the roulette wheel. These pockets could receive a 35:1 payout if hit straight up. If there's a split, the payout could be 17:1.