The $20 roulette strategy, otherwise known as the Martingale Strategy is an almost guaranteed way to make sure you win at the casino with $20. It works like this: Step One: Bet $20 on red, and if the ball lands on red you've won. You then proceed to take your money and stop playing, you've beaten the online casino.
From website "Groups and tours: Every day, except during the Formula 1 Grand Prix, the Casino de Monte-Carlo is open to groups and tours from 9 am till 12 pm only, so that games aren't disturbed."