Question

why 0! = 1
??......................??

Answer 1

factorial means selection so 0factorial consists of one selection of 0 factorial so ans is 1

Answer 2

hello friend ,
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SEE THE BASIC FIRST

•1! = 1
•2! = 1!*2
• 2! = 2
•3! = 2!*3
•3! = 6n
• 4! = 3!*4
•4! = 24
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1! = 1 n! = n*(n-1)! for n > 1

Now it is simple to change the definition to include 0! :

0! = 1 n! = n*(n-1)! for n > 0

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I HOPE IT HELPS :-)