Henry David Thoreau, an author and poet who died in 1862, said, “It is not worth the while to go round the world to count the cats in Zanzibar.”

I always thought that the key stat about Zanzibar is that the whole population of the world could stand on it. However, for a bridge player, this should become: It is worth the while to count as much as you can on every deal.

The hard part, of course, is working out what’s critical to count.

South is in three notrump. West leads a fourthhighest club two. How should East defend?

South’s two-heart rebid was a reverse, which promised a maximum opening and that his hearts were shorter than his diamonds: 17-20 points and at least 4-5 in the red suits.

East needs to count declarer’s hand distribution. West’s lead promised a fourcard suit, so South is known to have started with three clubs. Ergo, South probably has 1-4-5-3 distribution.

This should point East in the right direction. At trick two, he should shift to the spade king, just in case declarer has a singleton queen. Since East has diamonds under control, his side should be able to win five tricks before South collects nine. Even if West has the club king-jack, that suit can wait.

With the given layout, that’s exactly how the deal works out. Declarer ducks a couple of spades, wins the third round with dummy’s ace, and tries to run the diamonds. When they don’t break, he has to dislodge the club king to get out for down one.