A square is obtained by unfolding the sides of a cylinder. The height of the cylinder is known to be 31.4 cm. What is the area of its base in square centimeters?
把一个圆柱的侧面展开后得到一个正方形，已知圆柱的高是31.4厘米，它的底面积是多少平方厘米．
<gadget id="calculator">2 * 3.14</gadget>
<output>6.28</output>

<gadget id="calculator">31.4 / 6.28</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>