A park is in the shape of a circle. Grandpa walks around the park. There are exactly 628 steps in a circle. The average step length is 0.5 meters. What is the area of the park?
一个公园是圆形，爷爷绕着公园散步，走了一圈正好是628步，平均每步长0.5米，这个公园的面积是多少？
<gadget id="calculator">0.5 * 628</gadget>
<output>314</output>

<gadget id="calculator">314 / 3.14 / 2</gadget>
<output>50</output>

<gadget id="calculator">50 ** 2</gadget>
<output>2_500</output>

<gadget id="calculator">3.14 * 2_500</gadget>
<output>7_850</output>

<result>7_850</result>