SET IN ORDER *
Mr Knowall’s children have been using his favourite set of encyclopaedias for their homework research, but as usual they have not bothered to put them back in the correct order. In fact they are horribly jumbled.
Mr Knowall wants to put them back in order, but naturally, because each volume is very heavy, he wants to take as few volumes as possible off the shelf. If one move consists of taking a volume off the shelf, pushing some of the remaining books to one side and replacing the volume he took off, what is the smallest number of moves he requires?