The length of a rectangular piece of paper is 10 cm, and the width is 5 cm. If it is rotated around the width as the axis, what is the surface area of the figure formed?
一张长方形纸片的长是10厘米，宽是5厘米，如果以宽为轴旋转一周，形成的图形的表面积是多少平方厘米．
<gadget id="calculator">3.14 * 10 * 2 * 5</gadget>
<output>314</output>

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

<gadget id="calculator">3.14 * 100 * 2</gadget>
<output>628</output>

<gadget id="calculator">314 + 628</gadget>
<output>942</output>

<result>942</result>