steel pipe has a length of 100 cm, an outer diameter of 20 cm, and an inner diameter of 16 cm. Steel weighs 7.8 grams per cubic centimeter. How much does this steel pipe weigh in kilograms?
一只钢管，长100厘米，外直径20厘米，内直径是16厘米．每立方厘米钢重7.8克．这只钢管重多少千克？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<gadget id="calculator">8 ** 2</gadget>
<output>64</output>

<gadget id="calculator">100 - 64</gadget>
<output>36</output>

<gadget id="calculator">7.8 / 1_000</gadget>
<output>0.0078</output>

<gadget id="calculator">3.14 * 36 * 100 * 0.0078</gadget>
<output>88.1712</output>

<result>88.1712</result>