The outer circumference of the ring is 62.8 decimeters, and the inner circumference is 31.4 decimeters. Find the area of the ring.
环形的外圆周长为62.8分米，内圆周长为31.4分米，求环形的面积．
<gadget id="calculator">62.8 / 3.14 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</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">100 - 25</gadget>
<output>75</output>

<gadget id="calculator">3.14 * 75</gadget>
<output>235.5</output>

<result>235.5</result>