Master Wang needs to make three ventilation pipes with a bottom diameter of 20cm and a length of 120cm. How many square centimeters of iron sheet should be used at least?
王师傅要做3个底面直径是20cm，长是120cm的通风管，至少要用多少平方厘米的铁皮？
<gadget id="calculator">3.14 * 20 * 120 * 3</gadget>
<output>22_608</output>

<result>22_608</result>