If a cylindrical wood with a base radius of 1dm is cut into three sections, how much will the sum of the surface areas increase by dm**2.
把一个底面半径1dm的圆柱形木材横截成3段，表面积之和比原来增加多少dm**2．
<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1 * 4</gadget>
<output>12.56</output>

<result>12.56</result>