Rule of 7

This is rule associated with card play.

The rule of 7 tells you how long to hold up an ace when a suit is led against a NT contract especially 3NT.

If suit is 4/4 split then you can afford to lose 3 but safety play in case they are 5/3 is to count the number of cards you have in the suit between your hand and dummy.

So if your fit is 4-1 or 3-2 you take the 5 from 7 and that’s how many times you need to duck.

Example

		North
			J 6
			K J 7
			A 9 7 6
			9 5 4 2
West				East
	9 5				A 8 7 3 2
	Q T 6 5				9 3 2
	J T 8 5 4				K Q 2
	7 6				K 3
		South
			K Q T 4
			A 8 4
			3
			A Q J T 8

East opened 1NT (not the best bid but that’s what happened at my table)

South doubled and West made a weakness take out of 2.

North bid 3NT and East led K which was ducked.

Following with the DQ, declarer won with the A,

When East got in later with A she had another to lead to partner and the contract was defeated by one trick.

Had declarer known the rule of 7 he would have ducked twice – won the 3^rd

and made his contract with an overtrick as East has no more s to play when she got in with SA.

So N only loses 2 tricks and A.