In order to let the old trees survive the winter, the gardeners decided to wrap the old trees with straw ropes. He took a 101m long straw rope, wrapped it 20 times around the old tree, and found that there was still 52cm left. Use what you have learned to calculate the area of the cross section of this ancient tree.
园林工人为了更好地让古树过冬，决定用草绳把古树绕上．他拿来一根长101m的草绳，围着古树绕了20圈，发现还剩余52cm．用学过的知识计算这棵古树横截面的面积．
<gadget id="calculator">101 - 0.52</gadget>
<output>100.48</output>

<gadget id="calculator">100.48 / 20</gadget>
<output>5.024</output>

<gadget id="calculator">5.024 / 3.14 / 2</gadget>
<output>0.8</output>

<gadget id="calculator">0.8 ** 2</gadget>
<output>0.64</output>

<gadget id="calculator">3.14 * 0.64</gadget>
<output>2.0096</output>

<result>2.0096</result>