Xiao Ming walks along the outer edge of a circular pool for a week, exactly 50 steps, and the distance of each step is about 0.628 meters. What is the area of the pool in square meters?
小明沿着一个圆形水池的外沿走了一周，正好走了50步，每步的距离约是0.628米，这个水池的占地面积大约是多少平方米．
<gadget id="calculator">0.628 * 50</gadget>
<output>31.4</output>

<gadget id="calculator">31.4 / 3.14 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<result>78.5</result>