2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/125156Consider the set $\uu$ of real numbers $q \ge 1$ for which only one sequence $(c_i)$ of integers $0 \le c_i \le q$ satisfies the equality $\sum_{i=1}^{\infty} c_i q^{-i} = 1$. In this note we show that the set of algebraic numbers in $\uu$ is dense in the closure $\uuu$ of $\uu$.5 pages, journal version, to appear in Acta Math. HungarNumber TheoryPrimary: 11A63, Secondary:11B83text