In order to find if an integer is perfect, we need first to factor the number into prime factors.
For example, let's factor the number 16:
[tex]16=2\cdot2\cdot2\cdot2=2^4[/tex]Since the exponent of all prime factors is even, that means the number has a square root that is an integer:
[tex]\sqrt{16}=\sqrt{2^4}=2^{\frac{4}{2}}=2^2=4[/tex]Let's use another example: number 36:
[tex]\begin{gathered} 36=2\cdot2\cdot3\cdot3=2^2\cdot3^2 \\ \sqrt{36}=\sqrt{2^2\cdot3^2}=2\cdot3=6 \end{gathered}[/tex]