If a cylinder with a circumference of 6.28dm and a height of 20cm is cut along the diameter, how much will the surface area increase in cm**2.
将底面周长为6.28dm，高为20cm的圆柱沿直径切开，则表面积增加多少cm**2．
<gadget id="calculator">6.28 / 3.14</gadget>
<output>2</output>

<gadget id="calculator">2 * 10 * 2 * 10 * 2</gadget>
<output>800</output>

<result>800</result>