There is a cone-shaped stone whose height is measured to be 1.5 meters and the circumference of the base is 6.28 meters. Calculated based on the weight of 2.5 tons per cubic meter of stone, how many tons does this stone weigh?
有一块圆锥体的石头，量得它的高是1.5米，底面的周长是6.28米．按照每立方米石头重2.5吨计算，这块石头大约重多少吨？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">6.28 / 3.14 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">(1/3) * 3.14 * 1 * 1.5</gadget>
<output>1.57</output>

<gadget id="calculator">2.5 * 1.57</gadget>
<output>3.925</output>

<result>3.925</result>