The diameter of the chimney is 10 cm, and the length of each chimney is 2 meters. How much iron sheet does the school need to buy to make 15 such chimneys?
抽烟筒的直径是10厘米，每节抽烟筒长2米．学校要做15节这样的烟筒，需要买铁皮多少．
<gadget id="calculator">3.14 * 0.1 * 2</gadget>
<output>0.628</output>

<gadget id="calculator">0.628 * 15</gadget>
<output>9.42</output>

<result>9.42</result>