There are 12 buses running between Jammu and Delhi, In how many ways can a man go from Jammu to Delhi and return by a different bus?

If there are 20 steamers plying between places A and B, in how many ways could the round trip from A be made if the return was made on : a different steamer ?

If there are 20 steamers plying between places A and B, in how many ways could the round trip from A be made if the return was made on : the same steamer ?

A hall has 12 gates. In how many ways can a man enter the hall through one gate and come out through a different gate?

In how many ways can 5 sportsmen be selected from a group of 10 ?

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

A man has 7 friends. In how many ways can he invite one or more of them to a party ?

In how many ways can 5 different books be tied up in three bundles?

In how many ways can a team of 3 boys and 3 girls be selected from 5 boys and 4 girls?

A man has 10 friends. In how many ways he can invite one or more of them to a party?

In how many ways can 18 different books be divided equally among three students ?