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we know, 1! = 0!

this means: nPn = nPn-1

isn't that wrong? pl explan

THANK YOU

this is not true, 

1!=1

and 0!=1. there is a proof behind this.

nPn =n!/n! = 1

but, nPn-1 = n!/(n-1)! = n.

only because 1! = 0! we can't conclude that for all n belong to natural numbers nPn = nPn-1.

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hey vibhav, nPr = n!/(n-r)!

nPn-1 = n!/(n-(n-1))! = n!/(1)! = n!

nPn =n!/(n-n)! = n!/0! = n!

so, you're answer is not right

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sorry - "your"

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ya sorry

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whr did u get this frm

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 Yes offf course its correct. Here's its proof:

nPn=n!/(n-n)!= n!/0!=n! (Since 0!=1) ------(1)

nPn-1=n!/[n-(n-1)]!=n!/1!=n! [Since n-(n-1)=n-n+1=1] ----(2)

From 1 and 2 it is proved that

nPn= nPn-1.

Hope it helps!!

Cheers!!

Keep Smiling!!!

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