Master Li used tin to make a chimney with a diameter of 1 decimeter and a length of 1 meter. How many square meters of tin sheet is needed to make 25 knots? Seams are calculated as 1 cm.
李师傅用白铁皮制作直径是1分米、长是1米的烟囱．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>