Tap the blue circles to see an explanation.
| $$ \begin{aligned}6\sqrt{81}+6\sqrt{9}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}54+18 \xlongequal{ } \\[1 em] & \xlongequal{ }72\end{aligned} $$ | |
| ① | $$ 6 \sqrt{81} = 6 \cdot 9 = 54 $$ |
| ② | $$ 6 \sqrt{9} = 6 \cdot 3 = 18 $$ |