An enamel factory manufactures an iron box, which can be made from a circular iron sheet with a diameter of 0.4 meters. If 450 such iron boxes are produced every day, how many square meters of iron sheet are needed in total?
搪瓷厂制造一种铁盒，用直径为0.4米的圆形铁皮可以做成一个．如果每天生产450个这样的铁盒，共需铁皮多少平方米？
<gadget id="calculator">0.4 / 2</gadget>
<output>0.2</output>

<gadget id="calculator">0.2 ** 2</gadget>
<output>0.04</output>

<gadget id="calculator">3.14 * 0.04 * 450</gadget>
<output>56.52</output>

<result>56.52</result>