This calculates C(n,k). How many ways can k be chosen from n?

**Hold'em example:** How many possible flop combinations are there? You have two hole cards, leaving 50 cards in the deck. We are drawing three cards for the flop, so

**C(50,3) = 19,600** possible flop combinations.

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**Keno example:** How many possible

keno number combinations are there? There are 80 numbers total and 20 numbers are drawn, so

**C(80,20) = 3,535,316,142,212,174,000** possible number combinations. (Yes, 3.5 quintillion!)

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