Balti Tee 1992 · Ülesanne 7

Solution: The first of these numbers is less than the power tower obtained by replacing its topmost $a$ by $1992$. Since $a^{1992}=1992$, evaluating that larger tower from the top down gives $1992$ at every successive level. Hence the larger tower equals $1992$, so the first number is less than $1992$.