A cylindrical ventilation pipe is 100 cm high and 50 cm in diameter at the bottom. How many square meters of iron sheet is needed to make 100 such ventilation pipes?
一个圆柱形的通风管，高100厘米，底面直径50厘米，制作100个这样的通风管至少需要铁皮多少平方米．
<gadget id="calculator">3.14 * 50 * 100</gadget>
<output>15_700</output>

<gadget id="calculator">100 / 10_000</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">15_700 * (1/100)</gadget>
<output>157</output>

<result>157</result>