For what $x$ and $y$ is the number $\overline{x x y y}$ a square of a natural number?
The number $\overline{x x y y}$ is divisible by 11. If it is a perfect square, then the number $\overline{x 0 y}$ is also divisible by 11.
Answer
$88^{2}=7744$

## Problem

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