IMO Shortlist 2003 problem N2
Avg:
Avg:
Each positive integer
is subjected to the following procedure, yielding the number
:
(a) The last digit of
is moved to the first position. The resulting number is called
.
(b) The number
is squared. The resulting number is called
.
(c) The first digit of
is moved to the last position. The resulting number is called
.
(All numbers are considered in the decimal system.) For instance,
gives
,
and
.
Find all integers a such that
.


(a) The last digit of


(b) The number


(c) The first digit of


(All numbers are considered in the decimal system.) For instance,




Find all integers a such that

Izvor: Međunarodna matematička olimpijada, shortlist 2003