$\begin{array}{l} \text{Gegeben:}\\\text{Kreiszahl} \qquad \pi \qquad [] \\ \text{Radius} \qquad r \qquad [m] \\ \\ \text{Gesucht:} \\\text{Fläche} \qquad A \qquad [m^{2}] \\ \\ A = r^{2} \cdot \pi\\ \textbf{Gegeben:} \\ \pi=3\frac{16}{113} \qquad r=\frac{3}{10}m \qquad \\ \\ \textbf{Rechnung:} \\ A = r^{2} \cdot \pi \\ \pi=3\frac{16}{113}\\ r=\frac{3}{10}m\\ A = (\frac{3}{10}m)^{2} \cdot 3\frac{16}{113}\\\\A=0,283m^{2} \\\\ \small \begin{array}{|l|} \hline r=\\ \hline \frac{3}{10} m \\ \hline 3 dm \\ \hline 30 cm \\ \hline 300 mm \\ \hline 3\cdot 10^{5} \mu m \\ \hline \end{array} \small \begin{array}{|l|} \hline A=\\ \hline 0,283 m^2 \\ \hline 28,3 dm^2 \\ \hline 2,83\cdot 10^{3} cm^2 \\ \hline 2,83\cdot 10^{5} mm^2 \\ \hline 0,00283 a \\ \hline 2,83\cdot 10^{-5} ha \\ \hline \end{array} \end{array}$