~Rule of 11

If the leader leads fourth high, you can determine the number of cards outstanding by subtracting the number of the card led from 11. By examining the number of higher cards in the dummy and in your own hand, you can determine the number of cards in the forth hand higher than the card led.

LHO leads the spade 8 from
KJ983

Dummy’s spade holding is AQ2; declarer holds T4
in the suit.

By applying the Rule of 11, it appears that RHO holds no card higher than the 8 since 11-8 means the three hands, dummy, RHO, and declarer hold three cards higher than the 8. Declarer can duck the lead to hid T and then finesse LHO for the K at his leisure. The hands
North
AQ2

West
KJ983

East
765

South (D)
T4