A rectangular ventilation pipe has a cross-sectional area of a square. The side length of the square is 50 cm and the length is 8 meters. How many square meters of iron sheets are needed to make 50 such ventilation pipes?
一个长方形通风管，截面积是一个正方形，正方形的边长50厘米，长8米，做50个这样的通风管，需要多少平方米的铁皮？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 4 * 8 * 50</gadget>
<output>800</output>

<result>800</result>