The number of ways in which ten candidates A1, A2........A10 can be arranged in vertical row(column) when

1)if A1, A2 are next to each other. [9!.2!]

2)if A1 is just above A2. [9!]

3)if A1 is always above A2. [10!/2!]

4)if A1 is always above A2 and A2 is above A3 is.[10!/3!]

5)if A1, A2, A3 sit together in a specified order is. [8!]