if u play "21"
a set of card only have 52pcs....
basid average percentage is like...

a group of ppl of 4 + the house = 5
52 / 5 = 10 pcs  (starting each person 2 card)
so the percentage to gain big card 1/5 or 20% for each person

a group of 4 (sudah pakat) x 20%  = 80%
house only have = 20% winning.

so these 4 people will play strategy... kalah sikit, menang sedehana...sikit sikit lama jadi bukit.
mean they need to go in and out the casino for few days... when the casino tahu..they will backlist them.