For a cylindrical grain storage, if its height increases by 2 meters, its surface area will increase by 62.8 square meters. How many square meters does this grain storage occupy?
一个圆柱形粮囤，如果它的高增加2米，表面积就增加62.8平方米，这个粮囤占地多少平方米？
<gadget id="calculator">62.8 / 2</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>