A wire can enclose a square whose side length is 1.57 decimeters. If this iron wire encloses a circle, what is the area of the circle?
一根铁丝可以围成边长是1.57分米的正方形一个．如果把这根铁丝围成一个圆，这个圆的面积是多少平方分米？
<gadget id="calculator">4 / 3.14 / 2</gadget>
<output>0.636943</output>

<gadget id="calculator">1.57 * 0.636943</gadget>
<output>1.000001</output>

<gadget id="calculator">1.000001 ** 2</gadget>
<output>1.000002</output>

<gadget id="calculator">3.14 * 1.000002</gadget>
<output>3.140006</output>

<result>3.140006</result>