A section of the chimney made of iron sheets is 3 meters high, 40 cm in diameter, and 3 cm in the welded area. How many square meters of iron sheets are needed to manufacture this section of the chimney?
一节用铁皮卷成的烟囱高是3米，直径是40厘米，焊接的地方是3厘米，制造这节烟囱至少需要铁皮多少平方米．
<gadget id="calculator">3.14 * 0.4</gadget>
<output>1.256</output>

<gadget id="calculator">1.256 + 0.03</gadget>
<output>1.286</output>

<gadget id="calculator">1.286 * 3</gadget>
<output>3.858</output>

<result>3.858</result>