One Out Example
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"Gutshot Straight Flush Draw"
Although in this example you have outs to draw to a straight or flush, we're looking at your odds to catch a (royal) straight flush, the best hand possible in texas holdem.
You have only one card, the King of Spades, to make that hand. Chance of hitting your royal on the turn is 2.128%.
Overall the chance of hitting on the turn or river is 4.255%. If you miss it on the turn, your chances on the river are 2.174%.
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"Improving Three-of-a-Kind to Four-of-a-Kind"
Still talking about one out here. This would be your chance of turning your set into a four-of-a-kind. Your one out
is the only remaining Four in the deck, the Four of Hearts. Chances are the same as above.