A cylindrical chimney has a bottom diameter of 10 cm and a length of 80 cm; if it is extended to 150 cm, at least how many square centimeters of iron sheet should be added?
一根圆柱形烟筒，底面直径10厘米，长80厘米；如果加长到150厘米，至少需要增加多少平方厘米的铁皮？
<gadget id="calculator">150 - 80</gadget>
<output>70</output>

<gadget id="calculator">3.14 * 10 * 70</gadget>
<output>2_198</output>

<result>2_198</result>