If the circumference of a semicircle is 257 centimeters, what is its area in square centimetres?
一个半圆的周长是257厘米，它的面积是多少平方厘米．
<gadget id="calculator">3.14 / 2</gadget>
<output>1.57</output>

<gadget id="calculator">1.57 + 1</gadget>
<output>2.57</output>

<gadget id="calculator">257 / 2.57 / 2</gadget>
<output>50</output>

<gadget id="calculator">50 ** 2</gadget>
<output>2_500</output>

<gadget id="calculator">2_500 / 2</gadget>
<output>1_250</output>

<gadget id="calculator">3.14 * 1_250</gadget>
<output>3_925</output>

<result>3_925</result>