$$ \begin{aligned}\sqrt{18}\cdot\sqrt{18}& \xlongequal{ }\sqrt{324} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}18\end{aligned} $$ | |
① | The square root of $ 324 $ is $ 18 $. |