The middle part of a double-sided embroidery work is a circle with a diameter of 20cm. What is the area of the painting in cm**2.
一个双面绣作品中间部分的画是一个直径是20cm的圆．这幅画的面积是多少cm**2．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<result>314</result>