A sand pile approximately conical, with a bottom circumference of 18.84 meters and a height of 21 decimeters. If each cubic meter of sand weighs 2.5 tons, how many tons does the pile of sand weigh?
一个近似圆锥的沙堆，底面周长是18.84米，高21分米．如果每立方米沙子重2.5吨，这堆沙重多少吨？
<gadget id="calculator">2 * 3.14</gadget>
<output>6.28</output>

<gadget id="calculator">18.84 / 6.28</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">(1/3) * 3.14 * 9 * 2.1 * 2.5</gadget>
<output>49.455</output>

<result>49.455</result>