A 100-meter-long rope is wound 20 times around a big tree and the distance is 48 cm. What is the cross-sectional area of the big tree in cm**2.
将一根长100米的绳子绕一棵大树20圈少48cm，这棵大树的横截面面积是多少cm**2．
<gadget id="calculator">100 * 100</gadget>
<output>10_000</output>

<gadget id="calculator">10_000 + 48</gadget>
<output>10_048</output>

<gadget id="calculator">10_048 / 20 / 3.14 / 2</gadget>
<output>80</output>

<gadget id="calculator">3.14 * 80 * 80</gadget>
<output>20_096</output>

<result>20_096</result>