Dozen bet. A bet that the number will be in the chosen dozen: first (1-12, Premire douzaine or P12), second (13-24, Moyenne douzaine or M12), or third (25-36, Dernire douzaine or D12). Column bet.
First dozen / Premiere douzaine: numbers 1 - 12 (On the French-style mat, the square marked 12P) Middle dozen / Moyenne douzaine: numbers 13 - 24 (On the French-style mat, the square marked 12M)Last dozen / Dernier douzaine: numbers 25 - 36 (On the French-style mat, the square marked 12D)
This means that you cannot predict the exact number where the ball will land. But you only need to know which area of the wheel the ball will land and you can gain a massive advantage over the casino more than 40%.
While there is no strategy that can guarantee a profit in the long run when playing roulette, the Martingale betting system is often regarded as the most successful strategy. It is easy to use and can provide good returns.