A log with a length of 2 meters and a cross-sectional diameter of 40 cm is processed into the largest cuboid wood. If this kind of wood weighs 0.45 tons per cubic meter, how many tons does this cuboid wood weigh?
一根长2米的圆木，横截面的直径为40厘米，把它加工成一根最大的长方体木料．如果该种木料每立方米重0.45吨，这根长方体木料重多少吨？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">40 / 2 / 100 / 2</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(2/5) * (1/10) * 2 * 2 * 0.45</gadget>
<output>0.072</output>

<result>0.072</result>