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For the first set of cards, I would place four cards in this particular order---
4d, 5c, 10s and 9h. I would keep 6d the 'secrest card'.

For the second set of cards, I would place four cards in this particular order--Qh, 10s, 8d and 2c. I would keep 3h the 'secrest card'.

For the third set of cards, I would place four cards in this particular order---
Kh, 7c, 7d and 7s. I would keep 7h the 'secrest card'.

NOTE:There are 6 abbreviations used
c - Clubs
d - Diamonds
h - Hearts
s - Spades
Q - Queen
K - King