User:NineOfDiamonds/Rule of Eleven

Rule of Eleven

Introduction

The Rule of Eleven is a mathematical principle used in contract bridge. It can be employed anytime a defender leads his fourth-best card in any suit.

When a defender leads his fourth-best card in a suit, his partner (or declarer) subtracts the number of the card led from eleven. This yields the number of cards that are higher than the led card in the other three hands (i.e. other than the leader's hand).

Example: West leads the six of diamonds. East assumes that this is West's fourth-best diamond. East can see the eight and nine of the suit in dummy, and he holds the Ace and the ten himself.

He subtracts six from eleven, yielding five. So North, East and South collectively hold five diamonds higher than the six. Since East can see four of these, South (the declarer) must have only one. This information can be very useful to the defenders.