Cut a cylindrical wooden block with a bottom diameter of 16 cm and a height of 25 cm along the bottom diameter, and divide it into two parts with the same shape and size. How many square centimeters does their surface area increase from the original?
把一个底面直径是16厘米、高是25厘米的圆柱形木块沿底面直径切开，分成形状、大小完全相同的两部分，它们的表面积比原来增加了多少平方厘米？
<gadget id="calculator">16 * 25 * 2</gadget>
<output>800</output>

<result>800</result>