Three exhausted fishermen wash up on the beach with their haul, but are too sleepy to divide it up. At dawn, the first fisherman decides to take his 1/3 share and go home; this he does and throws the 1 leftover fish back into the sea. Second one, later unaware of the first, acts identically as does, finally the third one. So what is the minimum size of the original pile?
Apparently it was a Christmas tradition at St. John’s (University of Cambridge), where the math tutors would pose a riddle to incoming students. This was what Diarc was asked and his answer was -2.