A 2-meter-long steel casing has an outer diameter of 10 cm and a wall thickness of 2 cm. If the steel weighs 7.8 kg per cubic decimeter, how much does the steel casing weigh in total?
一根长2米的钢套管，外直径10厘米，管壁厚2厘米，如果每立方分米钢重7.8千克，这根钢套管共重多少千克？
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

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

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

<gadget id="calculator">10 - 4</gadget>
<output>6</output>

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

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

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

<gadget id="calculator">3.14 * 16 * 7.8</gadget>
<output>391.872</output>

<result>391.872</result>