If a log with a length of 4 meters and a cross-sectional diameter of 40 cm is sawn in half along the diameter, the surface area will increase by how many square meters.
把长为4米、横截面直径为40厘米的圆木沿直径锯成两半，表面积增加多少平方米．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 * (2/5) * 2</gadget>
<output>16/5 = around 3.2</output>

<result>16/5 = around 3.2</result>