The Rule of 7 for Hold-Up Plays
Subtract the number of cards you and dummy hold in the opponents' led suit from 7. The answer tells you how many times to duck your Ace.
When defending a 3NT contract, the opponents will lead their longest suit. If you hold the Ace, you must use the Rule of 7 to determine how many times to hold up (duck) before winning the trick to sever their communication.
Why the Rule of 7 works
The rule is a statistical shortcut. By subtracting your total holding in the suit from 7, you guarantee that the defender with the shorter holding will be exhausted of the suit. When that defender later wins a trick, they cannot return their partner's established suit.
A worked example: Ducking twice
West leads the ♠4 against 3NT.
Dummy: ♠ 7 5
Declarer: ♠ A 3 2
Caption: You hold 5 Spades combined (2 in dummy, 3 in hand). 7 - 5 = 2. You should hold up (duck) twice, winning the third round of Spades with your Ace. This mathematically ensures that if the Spades were split 5-3, the defender with 3 Spades is now void.
Four common mistakes
- Winning the Ace on Trick 1 automatically.
- Holding up when a shift to a different suit would be fatal.
- Miscounting the combined holding between declarer and dummy.
- Holding up when you already have 9 top tricks ready to cash.
When the rule does not apply
If the opponents threaten to shift to a much more dangerous suit, or if you hold two stoppers (e.g., A-K-x), the strict mathematical hold-up might cost you the contract. Adjust based on the layout.
Key takeaways
- Formula: 7 minus (Declarer's cards + Dummy's cards).
- The result equals the number of times to duck.
- Severs communication between defenders.
- Only applies in No-Trump contracts.