1. $n=9 \cdot \overline{a b}+(a+b)$, where $a+b<9$.

$\overline{a b}$ is a perfect square and $a+b<9 \Rightarrow \overline{a b} \in\{16 ; 25\}$.........................

$\Rightarrow n \in\{151 ; 232\}$
1. (7p) Determine the natural numbers which, when divided by 9, give a quotient of $\overline{a b}$ as a perfect square, and a remainder of $a+b$.

Maria Ghiță