MathDB
How many digits across all multiples of 1829?

Source: ISL 2022 N5

July 9, 2023
number theoryIMO ShortlistAZE IMO TST

Problem Statement

For each 1i91\leq i\leq 9 and TNT\in\mathbb N, define di(T)d_i(T) to be the total number of times the digit ii appears when all the multiples of 18291829 between 11 and TT inclusive are written out in base 1010.
Show that there are infinitely many TNT\in\mathbb N such that there are precisely two distinct values among d1(T)d_1(T), d2(T)d_2(T), \dots, d9(T)d_9(T).