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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- Mar 26th 2008, 04:42 PMGodKefkaNumber combinations ...
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 . - Mar 26th 2008, 04:50 PMgalactus
How many ways to choose 15 out of 25 numbers?.

C(25,15)=3,268,760 - Mar 26th 2008, 05:24 PMGodKefka
well... ok, but how to use this formula ?

- Mar 27th 2008, 03:56 AMgalactus
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. - Mar 27th 2008, 10:00 AMGodKefka
But I mean all possible combinations, without repeating them in a different order.