The metal ventilation pipe is 1 meter long, and the mouth of the pipe is a square with a side length of 3 decimeters. How many square meters of iron sheets are needed to make 100 such ventilation pipes?
铁皮通风管长1米，管口是边长3分米的正方形．做100个这样的通风管，需要多少平方米的铁皮？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * 4 * 1 * 100</gadget>
<output>120</output>

<result>120</result>