1) Considering that "perfect squares" are the numbers that yield square root exact numbers we can check the following list.
2) So we have:
[tex]\begin{gathered} \sqrt[]{361}=19 \\ \sqrt[]{225}=15 \\ \sqrt[]{36}=6 \\ \sqrt[]{121}=11 \\ \end{gathered}[/tex]So these are the perfect squares