$$ \begin{aligned}\frac{0.2}{1}\cdot\frac{0.4}{1}& \xlongequal{ }0\cdot0 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}0\end{aligned} $$ | |
① | $ 0 \cdot 0 = 0 $ |