There are 6 trains running between Indore and Bhopal . In how many ways can a man go from Indore to Bhopal and return by a different train ?

There are 6 trains running between New Delhi and Darbhanga. In how many ways can a man go from New Delhi to Darbhanga and return by a different trains?

There are 10 buses running between Delhi and Agra. In how many ways can a man go from Delhi to Agra and return by a different bus?

There are 15 buses running between Lucknow and Kanpur. In how many ways can a man go to Kanpur and return by a different bus?

There are 10 trains plying between Calcutta and Delhi. The number of ways in which a person can go from Calcutta to Delhi and return by a different train is:

From Goa to Mumbai there are 5 flights . In how many ways can Suresh go from Goa to Mumbai and return by a different flight ?

15 buses fly between Hyderabad and tirupati. The number of ways can a man go to tirupati from Hyderabad by a bus and return by a different bus is

There are 6 trains running between indore and Bhopal ., if the person can return by any one of the 6 trains , then find the number of ways in which he can go from indore to bhopal and return from bhopal to indore .

There are 4 routes between Delhi and Patna. In how many different ways can a man go from Delhi to Patna and return, if for returning
(i) any of the routes is taken,
(ii) the same route is taken,
(iii) the same route is not taken?

A room has 6 doors. In how many ways can a man enter the room through one door and come out through a different door?

A man has 6 friends. In how many ways can be invite one or more of his friends to a party ?