ASU 243 All Soviet Union MO 1977 7 elves around a table, each with cup
Source:
July 6, 2019
combinatoricscombinatorial geometry
Problem Statement
Seven elves are sitting at a round table. Each elf has a cup. Some cups are filled with some milk. Each elf in turn and clockwise divides all his milk between six other cups. After the seventh has done this, every cup was containing the initial amount of milk. How much milk did every cup contain, if there was three litres of milk total?