Grand slam force Grand slam force The Grand Slam Force is a bidding convention in contract bridge that was developed by Ely Culbertson in 1936. It is intended to be used in cases where the combined hands of a partnership are so strong that a slam (winning at least 12 tricks) is a near-certainty and a grand slam (winning all 13 tricks) is a possibility. It allows one partner to gain information on the quality of trumps in the other partner's hand. When this convention is in force, a bid of 5NT (five notrump), when it does not conflict with other conventions used
Contract bridge rounds, but in duplicate bridge, vulnerability is predetermined based on the number of each board. If the declaring side makes their contract, they receive points for , or tricks bid and made in excess of six. In both rubber and duplicate bridge, the declaring side is awarded 20 points per odd trick for a contract in clubs or diamonds, and 30 points per odd trick for a contract in hearts or spades. For a contract in notrump, the declaring side is awarded 40 points for the first odd trick and 30 points for the remaining odd tricks. Contract points are