A hollow steel pipe 100 cm long has an inner diameter of 6 cm and an outer diameter of 8 cm. (Steel weighs 0.0078 kg per cubic centimeter) How much does this steel pipe weigh in kilograms?
一根长100厘米的空心钢管，内直径是6厘米，外直径是8厘米．(每立方厘米钢重0.0078千克)这根钢管重多少千克．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

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

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

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

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<gadget id="calculator">50.24 - 28.26</gadget>
<output>21.98</output>

<gadget id="calculator">21.98 * 100</gadget>
<output>2_198</output>

<gadget id="calculator">2_198 * 0.0078</gadget>
<output>17.1444</output>

<result>17.1444</result>