A cylinder, when expanded laterally, is a square with a side length of 6.28 decimeters. If the cylinder is cut into two equal pieces along the diameter of the base, its surface area will increase by how many square decimeters.
一个圆柱体，侧面展开是一个边长6.28分米的正方形．如果沿底面直径将圆柱体切成相等的两块，它的表面积将增加多少平方分米．
<gadget id="calculator">6.28 / 3.14</gadget>
<output>2</output>

<gadget id="calculator">6.28 * 2 * 2</gadget>
<output>25.12</output>

<result>25.12</result>