If a cylinder with a base circumference of 6.28 decimeters and a height of 20 centimeters is cut along its diameter, how many square centimeters will the surface area increase?
将底面周长6.28分米，高20厘米的圆柱沿直径切开，则表面积增加多少平方厘米．
<gadget id="calculator">6.28 * 10</gadget>
<output>62.8</output>

<gadget id="calculator">62.8 / 3.14</gadget>
<output>20</output>

<gadget id="calculator">20 * 20 * 2</gadget>
<output>800</output>

<result>800</result>