Problem 2: I was hired to move a piano from one room to another.
Iâ€™m writing this from jail because one of the rooms was the main
stage at the new Bing Concert Hall at Stanford University (the
other was this guyâ€™s living room). My situation reminds me of a
problem: Part 2a: In a house with 10 rooms, how many ways are there
to move a piano from room A to room B and then to room C (A 6= B
and B 6= C). Part 2b: In a house with 10 rooms, how many ways are
there to move a piano ten times, visit all the other rooms exactly
once, with the last move ending the piano in the starting room?
(note: the piano must actually change rooms at each move.)