MathDB

15

Part of 1991 IMO Shortlist

Problems(1)

Does sequence become periodic after finite number of terms?

Source: IMO ShortList 1991, Problem 15 (USS 2)

8/15/2008
Let an a_n be the last nonzero digit in the decimal representation of the number n!. n!. Does the sequence a1,a2,…,an,… a_1, a_2, \ldots, a_n, \ldots become periodic after a finite number of terms?
factorialmodular arithmeticPeriodic sequenceIMO Shortlistdecimal representationDigits