When your partner leads a low card against notrump, subtract that card from 11. The result tells you the number of cards higher than the lead in the other three hands (dummy, your hand, and declarer’s hand).

Here’s an example: Partner leads the 6. 11 minus 6 equals 5. You can see 3 cards higher than the 6 in dummy, and you hold 2 cards higher than the 6 in your own hand. That accounts for all 5 — which means declarer has zero cards higher than the 6.

This is one of the most powerful defensive tools in bridge. It works because the standard opening lead convention is fourth-best from your longest and strongest suit. Since there are 14 cards in a suit above the deuce (well, 13 in total), and the leader holds the card they led plus three above it in their own hand — 14 minus 3 equals 11. That’s where the number comes from.

The Rule of 11 lets you:

– Know exactly how many high cards declarer holds in the suit led

– Make confident plays in third seat without guessing

– Signal accurately to partner based on what you’ve deduced

Try applying it at your next game. Once you see it work, you’ll never forget it.