There is a cylindrical hollow steel pipe with a length of 80 cm, an outer diameter of 10 cm and an inner diameter of 8 cm, find the volume of this steel pipe.
有一根长80cm的圆柱形空心钢管，外直径为10cm，内直径为8cm，求这根钢管的体积．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">25 - 16</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9 * 80</gadget>
<output>2_260.8</output>

<result>2_260.8</result>