A company wishes to simultaneously promote two of its 6 department heads out of 6 to assistant managers. In how many ways these promotions can take place?
From an organization of 6 persons, in how many ways can we choose a manager and senior manager assuming one person cannot hold more than one position?
Suppose 4 digits 2 ,4,6 and 9 are given. You have to make a four-digit number. In how many ways it can be done, if repetition of the numbers does not allowed?
