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)In square 12P or P12. On the middle 12 numbers, i.e. 12M or M12 (13-24) 2 to 1. In square 12M or M12. On the last 12 numbers, i.e. 12D or D12 (25-36)
