<=100 perfect squares - All-Russian MO 2001 Regional (R4) 9.8
Source:
September 26, 2024
number theoryPerfect SquareDigits
Problem Statement
Sasha wrote a non-zero number on the board and added it to it on the right, one non-zero digit at a time, until he writes out a million digits. Prove that an exact square has been written on the board no more than times.