Question

2!=2, 3!=6, 4!=24 & 0!= ' ? '

Answer 1

2! = 1×2 = 2
3! = 3×2×1 = 6
4! = 4×3×2×1 = 24
0! = ?
0! is 1
prof:
ⁿPn = n!/(n-r)!
ⁿPn = n(n-1)...….....4.3.2.1 = n!
ⁿPn = n!/(n-n)! ( putting r = n )
n! = n!/0!
0! = n!/n!
0! = 1

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