If a cylindrical steel bar with a length of 1 meter and a diameter of 4 decimeters at the bottom is cut into 2 sections, how much is the surface area increased by how many square decimeters?
把一根长1米，底面直径是4分米的圆柱形钢材截成2段，表面积增加了多少平方分米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<result>25.12</result>