Master Li uses white iron to make a chimney with a diameter of 1 decimeter and a length of 1 meter, and makes 25 knots. How many square meters of white iron is needed? (The seam is calculated as 1 cm)
李师傅用白铁皮制作直径1分米，长1米的烟囟，制作25节，大约需要白铁皮多少平方米？(接缝处按1厘米计算)
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">3.14 * (1/10)</gadget>
<output>0.314</output>

<gadget id="calculator">1 / 100</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">0.314 + (1/100)</gadget>
<output>0.324</output>

<gadget id="calculator">0.324 * 1 * 25</gadget>
<output>8.1</output>

<result>8.1</result>