Xiao Ming wraps a 314cm long rope around a tree exactly 10 times. What is the cross-sectional area of the tree in C㎡?
小明把一根长314cm的绳子在一棵树身上正好绕了10圈，这棵树身的横截面面积是多少C㎡？
<gadget id="calculator">314 / 10 / 3.14 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<result>78.5</result>