Boris is thinking about renovating the flat he just rented.
He walks up the stairs to the flat above his and asks the tenant, “Mr Trepper, you live directly above me and you have the same 2-room apartment as I do. How many rolls of wallpaper did you buy when you moved in?
“We got 48 rolls,” answers the neighbour.
Two months later Boris meets his neighbour again and says, “You know, it’s really funny – I put the wallpaper on everywhere and I still had 28 rolls left over.”
Mr Trepper smiles, “Yeah, so did we.“