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Brian Alspach
13 January 2000
The types of 3-card poker hands are
The total number of 3-card poker hands is
.
A straight flush is completely determined once the smallest card in the straight flush is known. There are 48 cards eligible to be the smallest card in a straight flush. Hence, there are 48 straight flushes.
In forming a 3-of-a-kind hand, there are 13 choices for the rank and
4 choices for the 3 cards of the given rank. This implies there are
3-of-a-kind hands.
The ranks of the cards in a straight have the form x,x+1,x+2, where
x can be any of 12 ranks. There are then 4 choices for each card of
the given ranks. This yields
total choices. However,
this count includes the straight flushes. Removing the 48 straight
flushes leaves us with 720 straights.
To count the number of flushes, we obtain
choices
for 3 cards in the same suit. Of these, 12 are straight flushes whose
removal leaves 274 flushes of a given suit. Multiplying by 4 produces
1,096 flushes.
Now we count the number of hands with a pair. There are 13 choices for
the rank of the pair, and
pairs of the chosen rank.
The non-pair card can be any of the remaining 48. Thus, there
are
3-card hands with a single pair.
We could determine the number of high card hands by removing the hands which have already been counted in one of the previous categories. Instead, let us count them independently and see if the numbers sum to 22,100 which will serve as a check on our arithmetic.
A high card hand has 3 distinct ranks, but does not allow ranks of the
form x,x+1,x+2 as that would constitute a straight. Thus, there are
possible sets of ranks from which we remove the
12 sets of the form
.
This leaves 274 sets of ranks.
For a given set 
of ranks, there are 4 choices for each card
except we cannot choose all in the same suit. Hence, there are
274(43-4) = 16,440 high card hands.
If we sum the preceding numbers, we obtain 22,100 and we can be confident the numbers are correct.
Here is a table summarizing the number of 3-card poker hands. The probability is the probability of having the hand dealt to you when dealt 3 cards.
| hand | number | Probability |
| straight flush | 48 | .0022 |
| 3-of-a-kind | 52 | .0024 |
| straight | 720 | .0326 |
| flush | 1,096 | .0496 |
| pair | 3,744 | .1694 |
| high card | 16,440 | .7439 |