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- RaymondLv 78 months ago
5! = 1*2*3*4*5

therefore

4! = 5! / 5 = 1*2*3*4 (the 5 cancels out)

therefore

3! = 4!/4

2! = 3!/3

1! = 2! / 2 = 1

therefore

0! = 1! / 1 = 1/1 = 1

It is the only way to make 0! consistent in the factorial operation.

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- JimLv 78 months ago
We ind factorials mostly in combinations and permutations.

To be consistent, we have defined 0! To be 1

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- Anonymous8 months ago
0! = 1 .

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- Anonymous8 months ago
The value of 0! is ****ZERO**** </shouting>

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- llafferLv 79 months ago
1

https://www.wolframalpha.com/input/?i=0%21

Another way to look at it is "how many ways can you arrange "n" objects".

If it was 3 objects, it's 6 ways.

If 2 objects, it's 2 ways.

If 1 object, it's 1 way.

If 0 objects, it's 1 way.

so 0! = 1

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- billrussell42Lv 79 months ago
The value of 0! is 1, according to convention.

see link for discussion on this.

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