"Like if I have 5 tshirts and i want to gift them to my 5 cousins named A,B,C,D,E, so find number of ways in which particular cousin won't get their particular tshirts."
So number of ways:
D(n)=n!*(1-1/1!+1/2!-1/3!+.....(-1)^n*1/n!))
Where n is number of things which don't go to their original position here in this question n = 5
So 5!*(1-1/1!+1/2!-1/3!+1/4!-1/5)) = 44 ways in which 5 tshirts won't go to their original position
D(1) = 0
D(2) = 1
D(3) = 2
D(4) = 9
D(5) = 44
D(6) = 265 (( remember these values of Dearangements )).
A prime number is the positive integer. (Besides ) which is divisible by 1 and itself. Examples: 2, 3, 5, 7, 11, 13, 17, 23, 29 etc. A number which is not prime is called a composite...
Math Phobia or math anxiety is a very real problem that many young students and even adult professionals face. What actually is Math Phobia? It is the doubt on one's mathematical abilities. How does...