Why does 0!=1?

Question

Why does 0!=1?

Answer 1

The ! means 1.  I remember this because they are on the same computer key.  Then you just add 0+!=1 or 0+1=1. It's that simple.  :-) Hope that Helped(-:

Answer 2

! means to multiply a number by the number minus 1 and continue doing this until you multiply the results by 1.  Example 5 * 4 * 3 * 2 * 1 = 120.  Notice factorial does not include zero so 0! = 1 is false.

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Answer 3

n! = n x (n-1)!

Let n=1

1! = 1 x (1-1)!

1! = 1 x (0)!

1 = 1 x (0!)

1 = 0!