Master Chen made 8 cylindrical ventilation pipes of the same size with iron sheets, the diameter is 20 cm, and each segment is 40 cm long. How many square centimeters of iron sheet are used in total? (not counting joints)
陈师傅用铁皮做8节同样大小的圆柱形通风管，直径是20厘米，每节长40厘米．一共用铁皮多少平方厘米？(接头处不计)
<gadget id="calculator">3.14 * 20 * 40 * 8</gadget>
<output>20_096</output>

<result>20_096</result>