TW-TST 1994 Problem 3

Let $a$ be a positive integer such that $5^{1994}-1\mid a$ . Prove that the expression of $a$ in base $5$ contains at least $1994$ nonzero digits.

Dataset text AI-MO AoPS. Quoted with source.

Solutions

No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.