MathDB
Product of digits NT

Source: BMO Shortlist 2022, N3

May 13, 2023
number theory

Problem Statement

For every natural number xx{}, let P(x)P(x) be the product of the digits of the number xx{}. Is there a natural number nn{} such that the numbers P(n)P(n) and P(n2)P(n^2) are non-zero squares of natural numbers, where the number of digits of the number nn{} is equal to (a) 2021 and (b) 2022?