A plastic product factory produces a washbasin, which is punched out of a circular plastic sheet with a diameter of 0.5 meters. How much plastic is needed to produce 800 washbasins of this kind?
塑料制品厂生产一种脸盆，是用直径为0.5米的圆形塑片冲压成的．生产这种脸盆800个，需塑片多少？
<gadget id="calculator">0.5 / 2</gadget>
<output>0.25</output>

<gadget id="calculator">0.25 ** 2</gadget>
<output>0.0625</output>

<gadget id="calculator">3.14 * 0.0625 * 800</gadget>
<output>157</output>

<result>157</result>