$\begin{array}{l} \text{Gegeben:}\\\text{Kreiszahl} \qquad \pi \qquad [] \\ \text{Radius} \qquad r \qquad [m] \\ \\ \text{Gesucht:} \\\text{Fläche} \qquad A \qquad [m^{2}] \\ \\ A = r^{2} \cdot \pi\\ \textbf{Gegeben:} \\ \pi=3\frac{16}{113} \qquad r=2\frac{1}{4}m \qquad \\ \\ \textbf{Rechnung:} \\ A = r^{2} \cdot \pi \\ \pi=3\frac{16}{113}\\ r=2\frac{1}{4}m\\ A = (2\frac{1}{4}m)^{2} \cdot 3\frac{16}{113}\\\\A=15,9m^{2} \\\\ \small \begin{array}{|l|} \hline r=\\ \hline 2\frac{1}{4} m \\ \hline 22\frac{1}{2} dm \\ \hline 225 cm \\ \hline 2,25\cdot 10^{3} mm \\ \hline 2,25\cdot 10^{6} \mu m \\ \hline \end{array} \small \begin{array}{|l|} \hline A=\\ \hline 15,9 m^2 \\ \hline 1,59\cdot 10^{3} dm^2 \\ \hline 1,59\cdot 10^{5} cm^2 \\ \hline 1,59\cdot 10^{7} mm^2 \\ \hline 0,159 a \\ \hline 0,00159 ha \\ \hline \end{array} \end{array}$