Rule of 11

In contract bridge, the Rule of 11 is applied when the opening lead is the fourth best from the defender's suit.^[1] By subtracting the rank of the card led from 11, the partner of the opening leader can determine how many cards higher than the card led are held by declarer, dummy and himself; by deduction of those in dummy and in his own hand, he can determine the number in declarer's hand.

^ Manley, Brent; Horton, Mark; Greenberg-Yarbro, Tracey; Rigal, Barry, eds. (2011). The Official Encyclopedia of Bridge (7th ed.). Horn Lake, MS: American Contract Bridge League. p. 588. ISBN 978-0-939460-99-1.

[1] Manley, Brent; Horton, Mark; Greenberg-Yarbro, Tracey; Rigal, Barry, eds. (2011). The Official Encyclopedia of Bridge (7th ed.). Horn Lake, MS: American Contract Bridge League. p. 588. ISBN 978-0-939460-99-1.

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