A section of cylindrical wood with a diameter and height of 20 cm is cut into two parts along its diameter. How much will the surface area of these two parts increase compared with the surface area of the original cylindrical wood.
把一段直径和高都是20厘米的圆柱形木料，沿着它的直径切成两部分，这两部分的表面积比原来这段圆柱形木料的表面积增加多少．
<gadget id="calculator">20 * 20 * 2</gadget>
<output>800</output>

<result>800</result>