Question

0factoriyal =1 how is possible
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Answer 1

Answer:

· = 120 permutations of a set with five elements. So an alternate way to think about the factorial is to let n be a natural number and say that n! is the number of permutations for a set with n elements. ... A set with one element has a single permutation, as the element 1 in the set {1} can only be ordered in one way.

Answer 2

Answer:

For r = n,

n |n

P = -----------------

n |n - n

|n

= ------------------

|0

Again,

n

P = n(n-1) (n-2)....... 2.1

n

= |n

|n

I. e. |n = -----------------

|0

✔ |0 = 1

Hope it helps....