IMO 1978 LL TUR39
A is a 2m-digit positive integer each of whose digits is 1. B is
IMO 1978 LL TUR39
Origin: TUR
Problem
A is a 2m-digit positive integer each of whose digits is 1. B is an m-digit positive integer each of whose digits is 4. Prove that A+B + 1 is a perfect square.