So... Let's say we have the numbers : 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 If you need to choose 15 of them , I would like to know what's all the possible combinations .
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How many ways to choose 15 out of 25 numbers?. C(25,15)=3,268,760
well... ok, but how to use this formula ?
Most calculators do combinations. That's what I used to do this one. The formula is $\displaystyle C(n,k)=\frac{n!}{(n-k)!k!}$ Do you know what a factorial is?. That's what the exclamation points are.
But I mean all possible combinations, without repeating them in a different order.
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