Baitie Factory produced 200 sections of ventilation pipes, each section is 2 meters long, and the circumference of the bottom surface is 6.28 decimeters. How many square meters of iron sheet should be used?
白铁厂生产了200节通风管，每节长2米，底面周长6.28分米．要用多少平方米的铁皮？
<gadget id="calculator">6.28 / 10</gadget>
<output>0.628</output>

<gadget id="calculator">0.628 * 2 * 200</gadget>
<output>251.2</output>

<result>251.2</result>