The classroom door is about 2 meters high and 1 meter wide. Now open the classroom door 90 degrees. How much space does the classroom door sweep?
教室的门高大约2米，宽大约1米，现在将教室的门打开90度，教室的门大约扫过了多大的空间？
<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3.14 * 1 * 2 * (1/4)</gadget>
<output>1.57</output>

<result>1.57</result>