A  room  has  6  doors. The no. of  ways,  in  which a  man can enter  the room through  one door  and come  out  through  a different  door,  is

Twenty persons were invited for a party.The different number of ways in which they can be seated on a circular table with two particular persons seated on either side of host is

The no.  of  ways in  which  a  committee  of 5  members  can be  selected  from 6  men and 5 women consisting  of  3  men and  2 women is

The  no. of  different  signals  that can  be   given  by  using  any no. of  flags, from  5 flags of different colors, is

If  P_m  stands  for  ^mP_m.  Then  the value  of 1+ P₁+2P₂+3P₃+......+n. P_n  is

The number of zeros at the end of 2007! is

In  how many  ways   (with  or without meaning)  a word  of three  alphabets of English  language  can be arranged if  repetition is not allowed?

The  no. of  5  digit  numbers that can  be formed  with the   digits 0,1,2,3,4  if the  numbers can be  repeated  in the same  number is

If (n+1)! = 56 (n-1)!,then n=