MathDB

Longest Tail on Perfect Squares

Source: 1989 IrMO Paper 1 Problem 4

September 29, 2017

number theory

Problem Statement

Note that

12^2=144

ends in two

4

s and

38^2=1444

end in three

4

s. Determine the length of the longest string of equal nonzero digits in which the square of an integer can end.