I assume most bridge players know the Odd-Even Rule.  Even if you do, a little reminder may be useful.  (Don’t you wish you had a memory like a computer where you could instantly recall anything you ever encountered - that is providing you knew where to look!)

 

The Odd Rule says that whenever there is an odd number of cards out against you, they most often divide as evenly as possible.  For instance, if you and dummy have eight cards in a suit, you should expect the other five to divide 3-2 between the two opponents.  This is no surprise as we all intuitively know to expect a 3-2 split more often than a 4-1 split.

 

The Even Rule says that whenever there is an even number of cards outstanding, they usually divide unevenly.  Thus when your side has seven in a suit (for example) you should expect the remaining six to divide 4-2 rather than 3-3.  This finding is not so obvious or intuitive as the Odd Rule.  So here are the statistics for the four-card and six-card situations:

 

(A)  With six cards outstanding:
           48% of the time they split 4-2.
           35% of the time they split 3-3.

 

(B)  When four cards are outstanding:
            50% of the time they split 3-1.
            41% of the time they split 2-2.