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Combinatorics 5.0/10

The Josephus Survivor

100 people stand in a circle, numbered 1 to 100. Starting the count at person 1, every second person is eliminated (so person 2 goes first), around and around until only one remains. What number survives?

Related problems & prerequisites

Worth solving first

Source: The Josephus problem, named for the account in Flavius Josephus; standard treatment in Graham, Knuth and Patashnik, 'Concrete Mathematics' (1989). Statement written for AxiomIQ.