Dearrangment Concept is very simple
Suppose that Normal question Is:
Q) How many 1-1 Function are possible on a Set with 6 elements, so that no element is mapped to itself ?
First , Dearrangment Formula clear in mind
There are 6 element
so
Number of Dearrangment Formula=6(1-1/1!+1/2!-1/3!+1/4!-1/5!+1/6!) Instead
And then Calculate Finally Answer is =265
This concept are Basically Clear for Dearrangment
