factoring

factoring
Message posted by Edward Bordner (via 203.172.6.109) on July 29, 2001 at 11:00 AM (ET)

Please show why 0!(zero factor) is equals to 1. Thank you very much.

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Re: factoring
Message posted by Jack Tomsky (via 209.86.5.65) on July 30, 2001 at 12:20 AM (ET)

The reason 0! is defined as equal to one is as follows.

The number of ways of choosing k items out of N is

C(N,k) = N!/[k!*(N-k)!].

Now suppose that k = N. We know that the number of ways of choosing N items out of N is one.

C(N,N) = N!/[N!*0!] = 1

Thus, 0! = 1.

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