What is the area of a roulette with a radius of 8 decimeters?
半径是8分米的轮盘，它的面积是多少平方分米．
<gadget id="calculator">8 ** 2</gadget>
<output>64</output>

<gadget id="calculator">3.14 * 64</gadget>
<output>200.96</output>

<result>200.96</result>