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I can choose 15 from 60 numbers (1 to 60), without any repetition.

e.g.: 1-5-10-15-20-25-30-35-40-45-50-55-57-58-59

How many different combinations can I choose?

Lucas NN
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    What did you try? What do you know so far about problems like these? – CPM Nov 25 '15 at 21:18
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    @CPM I know that if I can choose 6 elements, I will have 50.063.860 different combinations. But I don't know how to calculate with 15 elements. – Lucas NN Nov 25 '15 at 21:20

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So based on your comment above, I am assuming you know about combinations at least a bit. If there are $60$ people (think about them being labeled from 1 to 60) and you are picking a collection of $6$ to form a group, you apparently know that the answer is $\binom{60}{6}=50063860$. If you are doing the same thing with picking a collection of 15 numbers i.e. people, you just need to compute $\binom{60}{15}$.

$\binom{n}{k}=\frac{n!}{k!(n-k)!}$ Can you take it from here?

CPM
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